fix(audio+gps): lecture audio multi-navigateur + icône GPS dans tuile note

Audio :
- MediaRecorder détecte le format supporté : webm (Chrome/Firefox) ou mp4 (Safari/iOS)
- Extension sauvegardée correctement (.webm ou .m4a) selon le navigateur
- Backend : ALLOWED_AUDIO_PREFIXES remplace le set strict, strip des codec suffixes

GPS (note card) :
- Icône fa-location-dot (accent vert) avec tooltip lat/lon remplace l'emoji 📍

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/services/media.py

@@ -13,7 +13,7 @@ ALLOWED_IMAGE_TYPES = {
     "image/jpeg", "image/jpg", "image/png", "image/webp", "image/svg+xml",
     "image/heic", "image/heif",
 }
-ALLOWED_AUDIO_TYPES = {"audio/webm", "audio/mp4"}
+ALLOWED_AUDIO_PREFIXES = {"audio/webm", "audio/mp4", "audio/ogg", "audio/x-m4a"}
 
 MAX_ORIG_SIZE = (500, 500)
 
@@ -70,7 +70,8 @@ async def save_image(file: UploadFile, context: str = "note") -> dict:
 
 
 async def save_audio(file: UploadFile) -> dict:
-    if file.content_type not in ALLOWED_AUDIO_TYPES:
+    ct = (file.content_type or "").lower().split(";")[0].strip()
+    if ct not in ALLOWED_AUDIO_PREFIXES:
         raise HTTPException(status_code=400, detail=f"Format audio non supporté : {file.content_type}")
 
     file_id = str(uuid.uuid4())