feat: Phase 4 — module Notes complet

Backend :
- schemas/notes.py : NoteCreate/Update/Response + AttachmentResponse
- api/notes.py : CRUD + FTS français (plainto_tsquery) + filtres rapides
  (has_photo/audio/gps/tag/category) + pièces jointes (image/audio)
- main.py : enregistrement /api/notes

Frontend :
- api/notes.ts : fetchNotes/create/update/delete + add/deleteAttachment
- NoteForm.tsx : titre, contenu, catégorie, tags CSV, GPS
- NotesPage.tsx : liste mobile (chronologique) + grille laptop, FAB +,
  enregistrement audio inline (MediaRecorder), upload photo, filtres rapides

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

backend/app/main.py

@@ -4,6 +4,7 @@ from fastapi.middleware.cors import CORSMiddleware
 from fastapi.staticfiles import StaticFiles
 from app.api.health import router as health_router
 from app.api.media import router as media_router
+from app.api.notes import router as notes_router
 from app.api.todos import router as todos_router
 from app.api.shopping import router as shopping_router
 from app.core.config import settings
@@ -28,6 +29,7 @@ app.add_middleware(
 
 app.include_router(health_router, prefix="/api")
 app.include_router(media_router, prefix="/api/media")
+app.include_router(notes_router, prefix="/api/notes")
 app.include_router(todos_router, prefix="/api/todos")
 app.include_router(shopping_router, prefix="/api/shopping")