feat(precedents): metadata auto-fill, edit sheet, persuasive extraction

Three improvements to the precedent library based on usage feedback:

1. Auto-fill metadata at upload time. New service
   precedent_metadata_extractor reads the ruling's full_text and
   suggests case_name (short), summary, headnote, key_quote,
   subject_tags, appeal_subtype. The merge policy fills only empty
   fields, preserving everything the chair typed in the upload form.
   Wired into the ingest pipeline; also exposed as a re-run endpoint
   POST /api/precedent-library/{id}/extract-metadata for existing
   records.

2. Edit sheet in the UI. Pencil icon on each library row opens a
   pre-populated form covering every field. A Sparkles button on the
   sheet runs the metadata extractor on demand and refreshes the
   form. The case_number is read-only because halachot are FK'd to
   it; renaming requires delete + re-upload.

3. Halacha extractor branches on is_binding. Sources marked binding
   (Supreme/Administrative) keep the strict halacha prompt. Non-binding
   sources (other appeals committees, district courts on planning
   matters) get a different prompt that extracts applications,
   interpretive principles, and persuasive conclusions — labeled with
   new rule_types 'application' and 'persuasive'. The fallback also
   widens chunk selection: if the chunker labeled nothing as
   legal_analysis/ruling/conclusion, we now run on all chunks rather
   than returning zero halachot for a usable ruling.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

web/app.py

@@ -3779,6 +3779,37 @@ async def precedent_library_reextract(case_law_id: str):
     return {"task_id": task_id}
 
 
+@app.post("/api/precedent-library/{case_law_id}/extract-metadata")
+async def precedent_library_extract_metadata(case_law_id: str):
+    """Re-run metadata extraction in background. Fills empty fields only."""
+    try:
+        cid = UUID(case_law_id)
+    except ValueError:
+        raise HTTPException(400, "case_law_id לא תקין")
+    record = await db.get_case_law(cid)
+    if not record:
+        raise HTTPException(404, "פסיקה לא נמצאה")
+
+    task_id = str(uuid4())
+    label = record.get("case_number") or case_law_id
+    await _progress.set(task_id, {
+        "status": "queued", "filename": label, "stage": "queued", "percent": 0,
+    })
+    publish = _make_progress_publisher(task_id, label)
+
+    async def _run():
+        try:
+            await plib_service.reextract_metadata(cid, progress=publish)
+        except Exception as e:
+            logger.exception("re-extract metadata failed")
+            await _progress.set(task_id, {
+                "status": "failed", "error": str(e), "filename": label,
+            })
+
+    asyncio.create_task(_run())
+    return {"task_id": task_id}
+
+
 @app.get("/api/halachot")
 async def halachot_list(
     case_law_id: str = "",