prod: UI Optimisée mise en production

Fichiers mis en production:
- ✅ CSS modulaire (900+ lignes) - architecture 9 sections
- ✅ JavaScript moderne (600+ lignes) - state management complet
- ✅ Sauvegardes des fichiers originaux (.backup)
- ✅ Script de démarrage optimisé (START_WEB_OPTIMIZED.sh)
- ✅ Documentation déploiement (PRODUCTION_READY.md)

Changements CSS:
- 🏗️ Architecture modulaire avec CSS Variables
- ⚡ Animations GPU-optimisées (transform/opacity)
- ♿ prefers-reduced-motion implémenté
- 🎯 Focus visible pour accessibilité
- 📱 Responsive mobile-first
- 🎨 Design System V2 complet

Nouvelles fonctionnalités JS:
- 📦 State management centralisé (AppState)
- 🔐 Auth complète (login, register, logout)
- 🎵 Player controls: 8 boutons actifs
- 🍞 Toast notifications système
- ⌨️ Keyboard shortcuts (8 raccourcis)
- 📊 API intégrée (playlists, tracks)
- 🧭 Navigation SPA fluide
- 📱 Menu mobile responsive

Scripts:
- START_WEB_OPTIMIZED.sh - Script de démarrage optimisé

Documentation:
- PRODUCTION_READY.md - Guide complet de déploiement
- Instructions de démarrage
- Raccourcis clavier documentés
- Résolution de problèmes

Accessibilité:
- Focus states visibles
- Reduced motion support
- Touch targets 44x44px
- Contrast 4.5:1 minimum

Performance:
- Transform/opacity animations
- DOM elements cached
- Event delegation
- GPU accelerated

Generated with [Claude Code](https://claude.com/claude-code)
via [Happy](https://happy.engineering)

Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>

frontend/gradle/gradlew.bat

@@ -0,0 +1,90 @@
+@if "%DEBUG%" == "" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS=
+
+set DIRNAME=%~dp0
+if "%DIRNAME%" == "" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if "%ERRORLEVEL%" == "0" goto init
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto init
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:init
+@rem Get command-line arguments, handling Windowz variants
+
+if not "%OS%" == "Windows_NT" goto win9xME_args
+if "%@eval[2+2]" == "4" goto 4NT_args
+
+:win9xME_args
+@rem Slurp the command line arguments.
+set CMD_LINE_ARGS=
+set _SKIP=2
+
+:win9xME_args_slurp
+if "x%~1" == "x" goto execute
+
+set CMD_LINE_ARGS=%*
+goto execute
+
+:4NT_args
+@rem Get arguments from the 4NT Shell from JP Software
+set CMD_LINE_ARGS=%$
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %CMD_LINE_ARGS%
+
+:end
+@rem End local scope for the variables with windows NT shell
+if "%ERRORLEVEL%"=="0" goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
+exit /b 1
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega