feat: external precedent library with auto halacha extraction

Adds a third corpus of legal authority distinct from style_corpus
(Daphna's prior decisions for voice) and case_precedents (chair-attached
quotes per case). The new corpus holds chair-uploaded court rulings and
other appeals committee decisions, with binding rules (הלכות) extracted
automatically and queued for chair approval.

Pipeline (web/app.py + services/precedent_library.py):
file → extract → chunk → Voyage embed → halacha_extractor → store +
publish progress over the existing Redis SSE channel.

Schema V7 (services/db.py): extends case_law with source_kind +
extraction status fields under a CHECK constraint pinning practice_area
to the three appeals committee domains (rishuy_uvniya, betterment_levy,
compensation_197). New precedent_chunks (vector(1024)) and halachot
tables (vector(1024) over rule_statement, IVFFlat indexes, gin on
practice_areas/subject_tags). Halachot start as pending_review; only
approved/published rows are visible to search_precedent_library.

Agents: legal-writer, legal-researcher, legal-analyst, legal-ceo,
legal-qa get search_precedent_library. legal-writer prompt explains
the three-corpus distinction and CREAC use; legal-qa now verifies that
every cited halacha resolves to an approved row in the corpus.

UI: /precedents page with four tabs — library / semantic search /
pending review (J/K nav, A/R/E shortcuts, badge count) / stats.
Reuses the existing upload-sheet progress + SSE pattern.

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

web-ui/src/components/precedents/practice-area.ts

@@ -0,0 +1,37 @@
+/**
+ * Practice-area constants for the precedent library.
+ *
+ * The chair confined the library to the three appeals committee
+ * domains — no national-insurance corpus. The DB enforces this
+ * via a CHECK constraint on case_law.practice_area.
+ */
+
+export const PRACTICE_AREAS = [
+  { value: "rishuy_uvniya", label: "רישוי ובניה", short: "רישוי" },
+  { value: "betterment_levy", label: "היטל השבחה", short: "השבחה" },
+  { value: "compensation_197", label: "פיצויים לפי ס' 197", short: "פיצויים" },
+] as const;
+
+export const PRECEDENT_LEVELS = [
+  { value: "עליון", label: "עליון" },
+  { value: "מנהלי", label: "מנהלי" },
+  { value: "ועדת_ערר_ארצית", label: "ועדת ערר ארצית" },
+  { value: "ועדת_ערר_מחוזית", label: "ועדת ערר מחוזית" },
+] as const;
+
+export const SOURCE_TYPES = [
+  { value: "court_ruling", label: "פסק דין" },
+  { value: "appeals_committee", label: "החלטת ועדת ערר" },
+] as const;
+
+export function practiceAreaLabel(value: string | null | undefined): string {
+  if (!value) return "—";
+  const match = PRACTICE_AREAS.find((p) => p.value === value);
+  return match ? match.label : value;
+}
+
+export function practiceAreaShort(value: string | null | undefined): string {
+  if (!value) return "—";
+  const match = PRACTICE_AREAS.find((p) => p.value === value);
+  return match ? match.short : value;
+}