Fix scan infini: exclure dossiers transcoded et waveforms

Problème: Le scanner scannait TOUS les dossiers, y compris les dossiers
générés (transcoded/ et waveforms/), créant:
1. Boucle infinie: scan original → crée transcoded → re-scan transcoded
2. Segfaults: tentative de transcoder des fichiers déjà transcodés
3. Doublons en base de données

Solution:
- library.py: Exclut transcoded, waveforms, .transcoded, .waveforms
- scanner.py: Même exclusion dans le CLI

Technique: Modifie dirs[:] dans os.walk() pour skip ces dossiers.

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

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

backend/src/api/routes/library.py

@@ -41,6 +41,9 @@ def find_audio_files(directory: str) -> list[Path]:
         return []
 
     for root, dirs, files in os.walk(directory_path):
+        # Skip transcoded and waveforms directories
+        dirs[:] = [d for d in dirs if d not in ['transcoded', 'waveforms', '.transcoded', '.waveforms']]
+
         for file in files:
             file_path = Path(root) / file
             if file_path.suffix.lower() in AUDIO_EXTENSIONS:

backend/src/cli/scanner.py

@@ -46,6 +46,9 @@ def find_audio_files(directory: str) -> List[Path]:
     logger.info(f"Scanning directory: {directory}")
 
     for root, dirs, files in os.walk(directory_path):
+        # Skip transcoded and waveforms directories
+        dirs[:] = [d for d in dirs if d not in ['transcoded', 'waveforms', '.transcoded', '.waveforms']]
+
         for file in files:
             file_path = Path(root) / file
             if file_path.suffix.lower() in AUDIO_EXTENSIONS: