feat: Stage A finalizers + #35/#36/#37 — critical-gap closure

Four parallel sub-agents closed the remaining critical gaps from the
26/05 Stage A/B sprint. Each block independently tested; aggregated here.

## #30/#31 finalizers (sub-agent A)
* Auto-derive practice_area in case_create from case_number prefix
  (1xxx→rishuy_uvniya, 8xxx→betterment_levy, 9xxx→compensation_197);
  default for CaseCreateRequest is now "" (the DB constraint catches
  any stray "appeals_committee").
* practice_area.py: derive_subtype now handles axis-B domain values
  (rishuy_uvniya/betterment_levy/compensation_197) without parsing the
  case number; new helper derive_domain_practice_area().
* Halacha re-extraction verified unnecessary — all 6 reclassified
  records already had is_binding=false and approved halachot.
* Regression tests: 6 cases in tests/test_corpus_constraints.py
  covering practice_area enum, internal-committee chair/district,
  external-upload arar prefix, MCP guard.
* UI: district input → Select dropdown (7 districts) in
  precedent-edit-sheet.tsx, preserving legacy free-text values.

## #37 בל"מ subtypes (sub-agent B)
* 3 new appeal_subtypes: extension_request_{building_permit,
  betterment_levy,compensation}. APPEALS_COMMITTEE_SUBTYPES extended,
  SUBTYPES_BY_AREA mappings added.
* New helpers: is_blam_subject(), is_blam_subtype(),
  derive_subtype_with_blam(case_number, subject, practice_area).
  case_create now uses it to auto-detect "בקשה להארכת מועד" subjects.
* 3 methodology templates under docs/methodology/extension-request-*.md.
* paperclip_client.py mapping updated for the 3 new subtypes
  (extension_request_building_permit→CMP, the other two→CMPA).
* Frontend: bilingual "בל"מ" badge + filter dropdown on cases list +
  detail header; appeal-type-bars collapseBlam() merges בל"מ into its
  parent domain for aggregate bars.
* Wizard auto-detects בל"מ from subject during case creation.
* 3 Berlinger cases (1017/1018/1019-03-26) migrated to
  appeal_subtype=extension_request_building_permit via psql.

## #35 missing_precedents feature (sub-agent C)
* Schema V13: missing_precedents table (citation, case_id, party,
  legal_topic, status, linked_case_law_id, claim_quote, ...) +
  FK constraints + 3 indexes. Applied via psql + idempotent migration.
* 6 db.py service functions, 3 MCP tools, 6 FastAPI endpoints
  (POST/GET/PATCH/DELETE/upload — upload routes by citation prefix
  to ingest_internal_decision or ingest_precedent).
* Next.js page /missing-precedents with 5 status tabs + filters +
  sidebar badge counter + detail drawer with metadata edit + smart
  upload form that switches fields per committee/court.
* Bootstrap: 7 rows imported from the JSON file
  (3 citations × cases, all status=closed with linked_case_law_id).
* legal-researcher.md: new §2ב.5 with missing_precedent_create
  usage + dedup semantics + tool grant.

## #36 legal_arguments aggregation (sub-agent D)
* Schema V14: legal_arguments + legal_argument_propositions M:M.
  Applied via psql.
* New service argument_aggregator.py with two functions —
  aggregate_claims_to_arguments() (Claude CLI / claude_session) and
  get_legal_arguments(). Graceful llm_unavailable handling when CLI
  is missing (containers).
* 2 MCP tools + 2 API endpoints (POST .../aggregate-arguments as
  BackgroundTask, GET .../legal-arguments).
* Frontend: shadcn Accordion + new legal-arguments-panel.tsx with
  hierarchical (party → priority badge → arguments) display, "טיעונים"
  tab on the case page, "חשב/חשב מחדש" buttons.
* scripts/backfill_legal_arguments.py + SCRIPTS.md entry — dry-run
  found 8 candidate cases including 1017/1018/1019.

## Open follow-ups (intentionally deferred)
* npm run api:types in web-ui (CLAUDE.md flow) — recommended before
  the next UI commit; not required for backend deployment.
* Run backfill_legal_arguments.py --apply once the container picks up
  the new aggregator service.
* webhook on missing-precedents upload-close to Paperclip (optional).

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

web-ui/src/components/app-shell.tsx

@@ -15,6 +15,7 @@ import {
 } from "@/components/ui/dropdown-menu";
 import { GlobalSearch } from "@/components/global-search";
 import { headerSubtitle } from "@/components/header-context";
+import { useMissingPrecedentsOpenCount } from "@/lib/api/missing-precedents";
 
 /**
  * Ezer Mishpati navigation shell — two-row header.
@@ -45,9 +46,10 @@ const NAV_GROUPS: NavGroup[] = [
   {
     id: "knowledge",
     items: [
-      { href: "/precedents",  label: "ספריית פסיקה" },
-      { href: "/training",    label: "אימון סגנון" },
-      { href: "/methodology", label: "מתודולוגיה"  },
+      { href: "/precedents",          label: "ספריית פסיקה" },
+      { href: "/missing-precedents",  label: "פסיקה חסרה"  },
+      { href: "/training",            label: "אימון סגנון" },
+      { href: "/methodology",         label: "מתודולוגיה"  },
     ],
   },
 ];
@@ -240,7 +242,8 @@ function NavLink({ item, active }: { item: NavItem; active: boolean }) {
           : "text-parchment/80 hover:text-parchment hover:bg-navy-soft/60"}
       `}
     >
-      {item.label}
+      <span>{item.label}</span>
+      {item.href === "/missing-precedents" ? <MissingPrecedentsBadge /> : null}
       {active && (
         <span
           className="absolute -bottom-[19px] inset-x-2 h-[2px] bg-gold"
@@ -250,3 +253,18 @@ function NavLink({ item, active }: { item: NavItem; active: boolean }) {
     </Link>
   );
 }
+
+/* Small open-count badge next to "פסיקה חסרה" — only renders when >0
+ * so the nav stays quiet in normal operation. */
+function MissingPrecedentsBadge() {
+  const { data: openCount } = useMissingPrecedentsOpenCount();
+  if (!openCount) return null;
+  return (
+    <span
+      className="ms-1 inline-flex items-center justify-center min-w-[1.25rem] h-4 px-1 rounded-full bg-gold text-navy text-[0.65rem] font-semibold"
+      aria-label={`${openCount} פסיקות חסרות פתוחות`}
+    >
+      {openCount}
+    </span>
+  );
+}