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>

mcp-server/src/legal_mcp/tools/precedent_library.py

@@ -139,6 +139,19 @@ async def precedent_extract_halachot(case_law_id: str) -> str:
     return _ok(result)
 
 
+async def precedent_extract_metadata(case_law_id: str) -> str:
+    """חילוץ מטא-דאטה (case_name קצר, summary, headnote, key_quote, subject_tags, appeal_subtype) מהטקסט. ממלא רק שדות ריקים — לא דורס מה שכבר הוזן."""
+    try:
+        cid = UUID(case_law_id)
+    except ValueError:
+        return _err("case_law_id לא תקין")
+    try:
+        result = await precedent_library.reextract_metadata(cid)
+    except Exception as e:
+        return _err(str(e))
+    return _ok(result)
+
+
 async def search_precedent_library(
     query: str,
     practice_area: str = "",