Enhance README.md with installation instructions and usage examples for PLib video library manager.

scripts/run.bat

@@ -0,0 +1,36 @@
+@echo off
+setlocal
+
+rem Builds PLib and starts it. Any arguments are forwarded to the application.
+rem Usage:  run.bat [-c Release] [-- app args]
+
+set "ROOT=%~dp0.."
+set "PROJECT=%ROOT%\src\PLib.Desktop\PLib.Desktop.csproj"
+set "CONFIGURATION=Debug"
+
+if /i "%~1"=="-c" (
+    set "CONFIGURATION=%~2"
+    shift
+    shift
+)
+
+where dotnet >nul 2>&1
+if errorlevel 1 (
+    echo [PLib] dotnet SDK was not found in PATH. Install .NET 10 SDK first.
+    exit /b 1
+)
+
+rem ffmpeg is only needed at runtime, so a warning is enough to keep going.
+where ffmpeg >nul 2>&1
+if errorlevel 1 echo [PLib] Warning: ffmpeg is not in PATH - thumbnails will not be generated.
+
+echo [PLib] Building %CONFIGURATION%...
+dotnet build "%PROJECT%" -c %CONFIGURATION% --nologo
+if errorlevel 1 (
+    echo [PLib] Build failed.
+    exit /b 1
+)
+
+echo [PLib] Starting...
+dotnet run --project "%PROJECT%" -c %CONFIGURATION% --no-build -- %*
+exit /b %errorlevel%