feat(backend): endpoint POST /api/identify PlantNet + YOLO fallback + cache

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

backend/app/routers/identify.py

@@ -0,0 +1,29 @@
+from fastapi import APIRouter, File, UploadFile
+from app.services import plantnet, yolo_service, redis_cache
+
+router = APIRouter(tags=["identification"])
+
+
+@router.post("/identify")
+async def identify_plant(file: UploadFile = File(...)):
+    image_bytes = await file.read()
+
+    # 1. Cache Redis
+    cached = redis_cache.get(image_bytes)
+    if cached is not None:
+        return {"source": "cache", "results": cached}
+
+    # 2. PlantNet (cloud)
+    results = await plantnet.identify(image_bytes, file.filename or "photo.jpg")
+
+    # 3. Fallback YOLO si PlantNet indisponible
+    if not results:
+        results = await yolo_service.identify(image_bytes)
+        source = "yolo"
+    else:
+        source = "plantnet"
+
+    # 4. Mettre en cache
+    redis_cache.set(image_bytes, results)
+
+    return {"source": source, "results": results}