Improve LPR accuracy and add manual plate edit

- Tiled YOLO (3x2, 20% overlap): plate confidence 0.307 -> 0.838 on test frame
- Aspect ratio filter (2.0-6.5:1): rejects non-plate shapes
- Confidence threshold 0.03 -> 0.04: removes fence/noise false positives
- Exclude top 15% (sky) and bottom 8% (timestamp overlay) from detection zone
- Add Tesseract as primary OCR (better for Latin plates), PaddleOCR as fallback
- Enhance plate crop before OCR: CLAHE + sharpening + min 80px upscale
- Save plate_crop.jpg (4x upscaled) to event dir for manual review
- Show plate crop in event detail page
- Add manual plate edit form in event detail (POST /event/{id}/plate)

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

app/main.py

@@ -5,7 +5,7 @@ import threading
 import tempfile
 import asyncio
 from contextlib import asynccontextmanager
-from fastapi import FastAPI, Request, Query, HTTPException, UploadFile, File
+from fastapi import FastAPI, Request, Query, HTTPException, UploadFile, File, Form
 from fastapi.responses import HTMLResponse, RedirectResponse
 from fastapi.staticfiles import StaticFiles
 from fastapi.templating import Jinja2Templates
@@ -103,12 +103,16 @@ async def event_detail(request: Request, event_id: str):
         size = os.path.getsize(clip_abs)
         clip_size = f"{size // 1024 // 1024}MB" if size > 1024 * 1024 else f"{size // 1024}KB"
 
+    plate_crop_abs = os.path.join(event_dir, "plate_crop.jpg")
+    plate_crop = f"events/{event_id}/plate_crop.jpg" if os.path.exists(plate_crop_abs) else None
+
     return templates.TemplateResponse("event_detail.html", {
         "request": request,
         "ev": ev,
         "frames": frames,
         "has_clip": has_clip,
         "clip_size": clip_size,
+        "plate_crop": plate_crop,
         "capture_duration": CAPTURE_DURATION,
         "capture_fps": CAPTURE_FPS,
         "capture_total": CAPTURE_DURATION * CAPTURE_FPS,
@@ -136,6 +140,15 @@ async def api_events(
     return {"events": events, "total": total}
 
 
+@app.post("/event/{event_id}/plate")
+async def update_plate(event_id: str, plate: str = Form("")):
+    ev = database.get_event(event_id)
+    if not ev:
+        raise HTTPException(status_code=404, detail="Événement introuvable")
+    database.update_plate(event_id, plate)
+    return RedirectResponse(f"/event/{event_id}", status_code=303)
+
+
 @app.post("/upload")
 async def upload_clip(file: UploadFile = File(...)):
     if not file.filename.lower().endswith(".mp4"):