Add Windows DLL build workflow helpers

ddiff --git a/.github/workflows/windows-source-sdk-dlls.yml b/.github/workflows/windows-source-sdk-dlls.yml
nnew file mode 100644
iindex 0000000..28996b7
---- /dev/null
++++ b/.github/workflows/windows-source-sdk-dlls.yml
@@@ -0,0 +1,80 @@
++name: Build Windows Source DLLs
++
++on:
++  workflow_dispatch:
++  push:
++    branches:
++      - codex/openvibe-next-steps
++    paths:
++      - 'sdk/openvibe/**'
++      - 'game/openvibe.games/**'
++      - 'tools/build-sdk-windows.ps1'
++      - 'tools/build-quickjs-lib-windows.ps1'
++      - '.github/workflows/windows-source-sdk-dlls.yml'
++
++jobs:
++  windows-dlls:
++    name: Windows client.dll/server.dll
++    runs-on: windows-2022
++    timeout-minutes: 90
++
++    steps:
++      - name: Checkout OpenVibe
++        uses: actions/checkout@v4
++        with:
++          fetch-depth: 1
++
++      - name: Configure git line endings
++        shell: pwsh
++        run: |
++          git config --global core.autocrlf false
++
++      - name: Setup MSBuild
++        uses: microsoft/setup-msbuild@v2
++
++      - name: Show toolchain
++        shell: pwsh
++        run: |
++          where msbuild
++          where cl
++          git --version
++          pwsh --version
++
++      - name: Build Windows Source SDK DLLs
++        shell: pwsh
++        run: |
++          powershell -NoProfile -ExecutionPolicy Bypass -File tools\build-sdk-windows.ps1
++
++      - name: Stage artifacts
++        shell: pwsh
++        run: |
++          New-Item -Force -ItemType Directory artifact\game\openvibe.games\bin | Out-Null
++          New-Item -Force -ItemType Directory artifact\logs | Out-Null
++
++          $candidates = @(
++            "game\openvibe.games\bin\client.dll",
++            "game\openvibe.games\bin\server.dll",
++            "engine\source-sdk-2013\game\mod_hl2mp\bin\client.dll",
++            "engine\source-sdk-2013\game\mod_hl2mp\bin\server.dll",
++            "engine\source-sdk-2013\game\mod_hl2mp\bin\client.pdb",
++            "engine\source-sdk-2013\game\mod_hl2mp\bin\server.pdb"
++          )
++
++          foreach ($file in $candidates) {
++            if (Test-Path $file) {
++              Copy-Item $file artifact\game\openvibe.games\bin\ -Force
++            }
++          }
++
++          if (Test-Path "windows-build.log") {
++            Copy-Item windows-build.log artifact\logs\windows-build.log -Force
++          }
++
++          Get-ChildItem artifact -Recurse | Format-Table FullName,Length
++
++      - name: Upload Windows DLL artifact
++        uses: actions/upload-artifact@v4
++        with:
++          name: openvibe-windows-dlls
++          path: artifact/**
++          if-no-files-found: error
ddiff --git a/docs/BUILD_WINDOWS_DLLS_FROM_LINUX.md b/docs/BUILD_WINDOWS_DLLS_FROM_LINUX.md
nnew file mode 100644
iindex 0000000..d59057c
---- /dev/null
++++ b/docs/BUILD_WINDOWS_DLLS_FROM_LINUX.md
@@@ -0,0 +1,38 @@
++# Building Windows `client.dll` / `server.dll` from Linux
++
++OpenVibe supports two binary families:
++
++| Runtime | Client binary | Server binary | Notes |
++| --- | --- | --- | --- |
++| Native Linux Source | `game/openvibe.games/bin/linux64/client.so` | `game/openvibe.games/bin/linux64/server.so` | Built by the Linux SDK build. |
++| Windows / Proton Source | `game/openvibe.games/bin/client.dll` | `game/openvibe.games/bin/server.dll` | Must be built with a Windows/MSVC-compatible toolchain. |
++
++## Can Windows DLLs be built on Linux?
++
++Operationally, yes: trigger a Windows build from Linux using GitHub Actions:
++
++```bash
++git push
++tools/request-windows-dll-build.sh
++```
++
++That runs the build on a Windows runner, downloads the `openvibe-windows-dlls` artifact, and installs `client.dll` / `server.dll` into `game/openvibe.games/bin`.
++
++## Why not just MinGW?
++
++Source SDK 2013's Windows client/server DLLs are built around the MSVC ABI, Valve's VPC-generated Visual Studio projects, and Windows import/static libraries. A MinGW cross-compile from Linux is theoretically possible only after significant porting and import-library work, but it is not the practical path.
++
++## Reliable options
++
++1. **GitHub Actions Windows runner**: easiest from a Linux workstation.
++2. **Windows VM on Linux**: build with Visual Studio Build Tools/MSBuild, copy DLLs back.
++3. **Wine + Visual Studio Build Tools**: possible but brittle; treat as experimental.
++
++## Test
++
++```bash
++tools/check-openvibe-platform-binaries.sh
++OPENVIBE_CLIENT_MODE=proton tools/run-client-auto.sh 127.0.0.1 27015
++```
++
++If `client.dll` is present and correct, Proton's Windows `hl2.exe` should load OpenVibe client commands like `ov_join` and `ov_menu`.
ddiff --git a/tools/check-openvibe-platform-binaries.sh b/tools/check-openvibe-platform-binaries.sh
nnew file mode 100755
iindex 0000000..7aa34d3
---- /dev/null
++++ b/tools/check-openvibe-platform-binaries.sh
@@@ -0,0 +1,34 @@
++#!/usr/bin/env bash
++set -euo pipefail
++
++ROOT="${OPENVIBE_ROOT:-$HOME/src/openvibe-source}"
++cd "$ROOT"
++
++linux_bin="$ROOT/game/openvibe.games/bin/linux64"
++win_bin="$ROOT/game/openvibe.games/bin"
++
++echo "[openvibe] platform binary check"
++echo
++
++check_file() {
++  local label="$1"
++  local file="$2"
++  if [[ -f "$file" || -L "$file" ]]; then
++    echo "[ok]      $label: ${file#$ROOT/}"
++    file "$file" 2>/dev/null | sed 's/^/          /' || true
++  else
++    echo "[missing] $label: ${file#$ROOT/}"
++  fi
++}
++
++check_file "Linux client" "$linux_bin/client.so"
++check_file "Linux server" "$linux_bin/server.so"
++check_file "Windows client" "$win_bin/client.dll"
++check_file "Windows server" "$win_bin/server.dll"
++
++echo
++if [[ -f "$win_bin/client.dll" ]]; then
++  echo "[openvibe] Proton Windows hl2.exe should be able to load the OpenVibe client DLL."
++else
++  echo "[openvibe] Proton Windows hl2.exe will NOT have in-game ov_* client commands until client.dll exists."
++fi
ddiff --git a/tools/probe-local-windows-build-on-linux.sh b/tools/probe-local-windows-build-on-linux.sh
nnew file mode 100755
iindex 0000000..ca6c6d7
---- /dev/null
++++ b/tools/probe-local-windows-build-on-linux.sh
@@@ -0,0 +1,28 @@
++#!/usr/bin/env bash
++set -euo pipefail
++
++echo "[openvibe] local Windows build-on-Linux probe"
++echo
++echo "Pure MinGW cross-compile is not the recommended route for Source SDK 2013 client.dll."
++echo "The Windows Source client DLL needs the MSVC ABI/toolchain and Valve's Windows project layout."
++echo
++echo "What this host has:"
++
++for tool in wine wine64 cl link msbuild x86_64-w64-mingw32-g++ gh; do
++  if command -v "$tool" >/dev/null 2>&1; then
++    echo "[ok]      $tool -> $(command -v "$tool")"
++  else
++    echo "[missing] $tool"
++  fi
++done
++
++echo
++echo "Recommended from Linux:"
++echo "  1. Commit/push your branch."
++echo "  2. Run: tools/request-windows-dll-build.sh"
++echo "  3. Let GitHub Actions Windows runner build client.dll/server.dll with MSVC."
++echo
++echo "Experimental local path:"
++echo "  - Windows VM on Linux, or"
++echo "  - Wine with Visual Studio Build Tools installed, then run tools/build-sdk-windows.ps1 under that environment."
++echo "This is brittle; use the GitHub Actions/Windows runner first."
ddiff --git a/tools/request-windows-dll-build.sh b/tools/request-windows-dll-build.sh
nnew file mode 100755
iindex 0000000..2163e87
---- /dev/null
++++ b/tools/request-windows-dll-build.sh
@@@ -0,0 +1,80 @@
++#!/usr/bin/env bash
++set -euo pipefail
++
++ROOT="${OPENVIBE_ROOT:-$HOME/src/openvibe-source}"
++cd "$ROOT"
++
++WORKFLOW="${OPENVIBE_WINDOWS_WORKFLOW:-windows-source-sdk-dlls.yml}"
++ARTIFACT="${OPENVIBE_WINDOWS_ARTIFACT:-openvibe-windows-dlls}"
++BRANCH="${OPENVIBE_BRANCH:-$(git rev-parse --abbrev-ref HEAD)}"
++OUT_DIR="${OPENVIBE_WINDOWS_ARTIFACT_DIR:-$ROOT/.tmp/windows-dll-artifact}"
++
++if ! command -v gh >/dev/null 2>&1; then
++  echo "Missing GitHub CLI: gh" >&2
++  echo "Install it, then run: gh auth login" >&2
++  exit 1
++fi
++
++if ! gh auth status >/dev/null 2>&1; then
++  echo "gh is not authenticated. Run: gh auth login" >&2
++  exit 1
++fi
++
++if [[ -n "$(git status --porcelain)" ]]; then
++  echo "[openvibe] WARNING: working tree has uncommitted changes."
++  echo "[openvibe] GitHub Actions builds the pushed branch, not your uncommitted local files."
++  echo
++  git status --short
++  echo
++  read -r -p "Continue anyway? [y/N] " answer
++  [[ "$answer" =~ ^[Yy]$ ]] || exit 1
++fi
++
++echo "[openvibe] triggering GitHub Actions Windows DLL build"
++echo "[openvibe] workflow=$WORKFLOW branch=$BRANCH"
++
++gh workflow run "$WORKFLOW" --ref "$BRANCH"
++
++echo "[openvibe] waiting for run to appear..."
++RUN_ID=""
++for _ in {1..30}; do
++  RUN_ID="$(gh run list --workflow "$WORKFLOW" --branch "$BRANCH" --limit 1 --json databaseId,status,event -q '.[0].databaseId // empty' 2>/dev/null || true)"
++  [[ -n "$RUN_ID" ]] && break
++  sleep 2
++done
++
++if [[ -z "$RUN_ID" ]]; then
++  echo "Could not find the workflow run. Check GitHub Actions UI." >&2
++  exit 1
++fi
++
++echo "[openvibe] watching run $RUN_ID"
++gh run watch "$RUN_ID" --exit-status
++
++rm -rf "$OUT_DIR"
++mkdir -p "$OUT_DIR"
++
++echo "[openvibe] downloading artifact $ARTIFACT"
++gh run download "$RUN_ID" --name "$ARTIFACT" --dir "$OUT_DIR"
++
++echo "[openvibe] downloaded files:"
++find "$OUT_DIR" -type f -maxdepth 8 -print | sort
++
++echo
++echo "[openvibe] installing Windows DLLs into game/openvibe.games/bin"
++mkdir -p "$ROOT/game/openvibe.games/bin"
++
++find "$OUT_DIR" -type f \( -iname 'client.dll' -o -iname 'server.dll' -o -iname 'client.pdb' -o -iname 'server.pdb' \) -print0 |
++while IFS= read -r -d '' file; do
++  cp -f "$file" "$ROOT/game/openvibe.games/bin/$(basename "$file")"
++  echo "  installed $(basename "$file")"
++done
++
++echo
++"$ROOT/tools/check-openvibe-platform-binaries.sh" || true
++
++echo
++echo "[openvibe] done."
++echo "Proton/Windows can use:"
++echo "  game/openvibe.games/bin/client.dll"
++echo "  game/openvibe.games/bin/server.dll"