Ajout documentation dépendances + script de vérification

- DEPENDENCIES.md: Documentation complète de toutes les dépendances
  * Backend Python (requirements.txt)
  * Dépendances système (apt packages)
  * Frontend Node.js (package.json)
  * Modèles Essentia (28 MB)
  * Variables d'environnement requises

- check_dependencies.py: Script pour vérifier l'installation
  * Teste tous les imports Python
  * Affiche statut ✅/❌ pour chaque package
  * Utile pour debug d'installation

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

backend/check_dependencies.py

@@ -0,0 +1,76 @@
+#!/usr/bin/env python3
+"""Check all required dependencies are installed."""
+import sys
+
+def check_import(module_name, package_name=None):
+    """Try to import a module and report status."""
+    package = package_name or module_name
+    try:
+        __import__(module_name)
+        print(f"✅ {package}")
+        return True
+    except ImportError as e:
+        print(f"❌ {package}: {e}")
+        return False
+
+def main():
+    """Check all dependencies."""
+    print("🔍 Checking Python dependencies...\n")
+
+    dependencies = [
+        # Web Framework
+        ("fastapi", "fastapi"),
+        ("uvicorn", "uvicorn"),
+        ("multipart", "python-multipart"),
+
+        # Database
+        ("sqlalchemy", "sqlalchemy"),
+        ("psycopg2", "psycopg2-binary"),
+        ("pgvector.sqlalchemy", "pgvector"),
+        ("alembic", "alembic"),
+
+        # Audio Processing
+        ("librosa", "librosa"),
+        ("soundfile", "soundfile"),
+        ("audioread", "audioread"),
+        ("mutagen", "mutagen"),
+
+        # Scientific
+        ("numpy", "numpy"),
+        ("scipy", "scipy"),
+
+        # Configuration
+        ("pydantic", "pydantic"),
+        ("pydantic_settings", "pydantic-settings"),
+        ("dotenv", "python-dotenv"),
+        ("email_validator", "email-validator"),
+
+        # Authentication
+        ("jose", "python-jose"),
+        ("passlib", "passlib"),
+
+        # Utilities
+        ("aiofiles", "aiofiles"),
+        ("httpx", "httpx"),
+
+        # Essentia (optional)
+        ("essentia.standard", "essentia-tensorflow"),
+    ]
+
+    all_ok = True
+    for module, package in dependencies:
+        if not check_import(module, package):
+            all_ok = False
+
+    print("\n" + "="*50)
+    if all_ok:
+        print("✅ All dependencies installed!")
+        return 0
+    else:
+        print("❌ Some dependencies are missing")
+        print("\nInstall missing dependencies with:")
+        print("  pip install -r requirements.txt")
+        return 1
+
+if __name__ == "__main__":
+    sys.exit(main())