feat: bundle FFmpeg via ffmpeg-static for one-click deployment

Users no longer need to install FFmpeg separately — it is now bundled as
an npm dependency (ffmpeg-static). player.ts resolves the bundled binary
automatically and falls back to system PATH. start.bat and a new
setup.bat script handle dependency installation and project building.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

scripts/start.bat

@@ -6,34 +6,42 @@ echo.
 :: Check if node is available
 where node >nul 2>&1
 if %errorlevel% neq 0 (
-    echo Node.js is not installed. Please install Node.js 20 LTS from https://nodejs.org
+    echo Node.js is not installed.
+    echo Run scripts\setup.bat for automatic installation, or install Node.js 20+ from https://nodejs.org
     pause
     exit /b 1
 )
 
-:: Check if ffmpeg is available
-where ffmpeg >nul 2>&1
-if %errorlevel% neq 0 (
-    echo FFmpeg not found in PATH. Checking local directory...
-    if exist "%~dp0ffmpeg\ffmpeg.exe" (
-        set PATH=%~dp0ffmpeg;%PATH%
-        echo Using bundled FFmpeg.
-    ) else (
-        echo FFmpeg is required. Please install FFmpeg or place it in the ffmpeg\ directory.
+:: Resolve project root (one level up from scripts/)
+cd /d "%~dp0.."
+
+:: Install dependencies if needed
+if not exist "node_modules" (
+    echo Installing dependencies...
+    call npm install --production
+    if %errorlevel% neq 0 (
+        echo Failed to install dependencies.
         pause
         exit /b 1
     )
 )
 
-:: Install dependencies if needed
-if not exist "%~dp0node_modules" (
-    echo Installing dependencies...
-    cd /d "%~dp0"
-    call npm install --production
+:: Build if dist/ doesn't exist
+if not exist "dist" (
+    echo Building project...
+    call npx tsc
+    if %errorlevel% neq 0 (
+        echo Build failed.
+        pause
+        exit /b 1
+    )
 )
 
+:: FFmpeg is bundled via ffmpeg-static — no PATH check needed.
+echo FFmpeg is bundled via node_modules (ffmpeg-static).
+echo.
+
 :: Start the application
-cd /d "%~dp0"
 node dist/index.js
 
 pause