fix(halacha): split authority (derived) from rule_role — stop source-conflation (INV-DM7)

The extractor classified rule_type by SOURCE bindingness (higher-court→binding,
committee→persuasive) instead of by rule KIND. The gold-set proved it: 'binding'
appeared on 19/19 external rulings & 0 committees; 'persuasive' on 13/13
committees & 0 external — only 58% agreement with the human role tags. The two
axes (authority vs rule role) were crammed into one enum.

This splits them per INV-DM7:
- authority (binding/persuasive) — DERIVED from case_law.precedent_level
  (עליון/מנהלי→binding, ועדת_ערר_מחוזית→persuasive), never stored, never
  LLM-guessed. New helper halacha_quality.derive_authority; surfaced read-only
  in list_halachot / goldset_list / search results.
- rule_type — now the rule ROLE only: holding/interpretive/procedural/
  application/obiter. Both extractor prompts unified to this vocabulary;
  _coerce_halacha no longer defaults rule_type from the source; legacy
  binding→holding / persuasive→interpretive fold for safety.

UI: authority shown as a separate read-only badge (gold=מחייב / muted=משכנע)
across the review queue, precedent detail, and gold-set; the gold-set role
selector drops binding/persuasive and adds מהותי (holding).

Migration: scripts/halacha_rule_role_backfill.py re-classifies the 276 pre-split
binding/persuasive rows into a genuine role via local claude_session (run after
deploy). Gold-set correct_type/ai_correct_type 'binding'→'holding' via SQL.

Sources (≥3, per research-decision policy): OASIS LegalRuleML v1.0
(appliesAuthority/Strength as metadata orthogonal to rule logic) · SemEval-2023
Task 6 LegalEval (rhetorical roles by function, authority kept separate) ·
Bluebook signals (weight-of-authority is a separate dimension).

Invariants: ESTABLISHES INV-DM7. Upholds G1 (normalize at source — extractor
classifies role, system derives authority) and G2 (single source of truth —
authority derived, not a parallel stored field). Tests: 211 pass + new
derive_authority/coerce coverage. web-ui build + tsc clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

web-ui/src/lib/api/precedent-library.ts

@@ -65,6 +65,8 @@ export type Halacha = {
   halacha_index: number;
   rule_statement: string;
   rule_type: string;
+  // authority over the committee — DERIVED from the source (INV-DM7), read-only.
+  authority?: "binding" | "persuasive" | null;
   reasoning_summary: string;
   supporting_quote: string;
   page_reference: string;
@@ -138,6 +140,7 @@ export type SearchHit =
       subject_tags: string[];
       confidence: number;
       rule_type: string;
+      authority?: "binding" | "persuasive" | null;
       case_number: string;
       case_name: string;
       court: string;