feat(proceeding-type): explicit ערר/בל"מ field for cases + corpus

Same case_number can exist as both a regular appeal (ערר) and an
extension-of-time request (בל"מ), and we were inferring the difference
from appeal_subtype prefixes — fragile, and case-number lookups
weren't disambiguated. Now stored as a first-class field on both
case_law (corpus) and cases (live cases), with partial unique indexes
on (case_number, proceeding_type).

- SCHEMA_V15: column + CHECK constraints + backfill from
  appeal_subtype LIKE 'extension_request_%' + partial unique indexes
  replace the old global UNIQUE(case_number).
- derive_proceeding_type() centralizes the inference rule
  (extension_request_* → בל"מ; subject regex fallback; default ערר).
- Metadata extractor prompt asks Claude to populate the new field
  explicitly; apply_to_record writes it for internal_committee rows.
- internal_decision_upload, case_create, case_update accept an
  optional proceeding_type; FastAPI request models expose it.
- Wizard + edit dialog get a sided Select; case header renders the
  resolved label (ערר / בל"מ).
- Uploaded the 2 staged בל"מ decisions on betterment levy:
  8126/24 (סופר נוח, 13 chunks), 8047/23 (הרנון, 48 chunks).

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

mcp-server/src/legal_mcp/services/internal_decisions.py

@@ -24,6 +24,7 @@ from uuid import UUID, uuid4
 
 from legal_mcp import config
 from legal_mcp.services import chunker, db, embeddings, extractor
+from legal_mcp.services.practice_area import derive_proceeding_type
 
 logger = logging.getLogger(__name__)
 
@@ -86,11 +87,13 @@ async def ingest_internal_decision(
     text: str | None = None,
     document_id: UUID | None = None,
     queue_halachot: bool = True,
+    proceeding_type: str = "",
 ) -> dict:
     """Ingest an appeals-committee decision into the internal corpus.
 
     Either file_path or text must be provided.
     If district is empty, it is inferred from court.
+    If proceeding_type is empty, it is derived from appeal_subtype/case_name.
     Returns: {"status": "completed", "case_law_id": "...", "chunks": N}
     """
     if not file_path and not text:
@@ -99,6 +102,9 @@ async def ingest_internal_decision(
         raise ValueError("case_number is required")
 
     resolved_district = district.strip() or _district_from_court(court)
+    resolved_proc = proceeding_type.strip() or derive_proceeding_type(
+        appeal_subtype=appeal_subtype, subject=case_name,
+    )
 
     if file_path:
         src = Path(file_path)
@@ -133,6 +139,7 @@ async def ingest_internal_decision(
         summary=summary.strip(),
         is_binding=is_binding,
         document_id=document_id,
+        proceeding_type=resolved_proc,
     )
     case_law_id = UUID(str(record["id"]))