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/api/notes.py

@@ -9,7 +9,7 @@ from app.core.database import get_session
 from app.core.redis import enqueue
 from app.models.notes import NoteItem, NoteAttachment
 from app.schemas.notes import NoteCreate, NoteUpdate, NoteResponse
-from app.services.media import save_image, save_audio, delete_media, ALLOWED_IMAGE_TYPES, ALLOWED_AUDIO_TYPES
+from app.services.media import save_image, save_audio, delete_media, ALLOWED_IMAGE_TYPES, ALLOWED_AUDIO_PREFIXES
 
 router = APIRouter()
 
@@ -130,10 +130,11 @@ async def add_attachment(
     if not note:
         raise HTTPException(404, "Note introuvable")
 
-    if file.content_type in ALLOWED_IMAGE_TYPES:
+    ct = (file.content_type or "").lower().split(";")[0].strip()
+    if ct in ALLOWED_IMAGE_TYPES:
         media = await save_image(file, context="note")
         file_type = "image"
-    elif file.content_type in ALLOWED_AUDIO_TYPES:
+    elif ct in ALLOWED_AUDIO_PREFIXES:
         media = await save_audio(file)
         file_type = "audio"
     else: