feat(halacha): application gate + lexical dedup tail + quality harnesses (#81,#82)

Halacha-extraction quality (#81) and dedup-on-insert (#82) — engine changes
(pure + tested) plus measurement/ops tooling.

halacha_quality.py
- #81.4 application gate: is_fact_dependent() (high-precision "applied to THIS
  case" deixis per the strict rubric §3/§27) + FLAG_APPLICATION. compute_quality_flags
  now takes rule_type and flags rule_type=='application' OR fact-dependent —
  blocking auto-approve (an illustration is not a generalizable holding).
- #82.3 lexical tail signal: jaccard_shingles / normalized_levenshtein /
  lexical_near_duplicate + FLAG_NEAR_DUPLICATE, for the 0.83–0.93 cosine band.

halacha_extractor.py — pass rule_type to the flag computation; re-type a
binding-labeled fact-application to 'application' (mirrors non_decision→obiter).

db.py (store_halachot_for_chunk) — dedup now fetches the nearest same-precedent
neighbor once: cosine ≥ DEDUP → skip (unchanged); cosine in [BAND, DEDUP) with
high lexical overlap → FLAG_NEAR_DUPLICATE (review, not skip — never drop a
possibly-distinct principle unreviewed).

config.py — HALACHA_DEDUP_BAND_COSINE (0.83).

Scripts:
- scripts/halacha_goldset.py (#81.7) — export stratified sample for human
  tagging; score validators (P/R/F1) against the tags. Backbone for #81.8.
- scripts/halacha_batch_reconcile.py (#82.7) — conservative cross-precedent
  dedup (cosine ≥0.95), dry-run report only.
- scripts/calibrate_halacha_dedup.py (#82.1) — calibrate the lexical thresholds
  against the 2026-06-03 cleanup gold-set.

Deferred (documented): #82.4 merge-provenance and #82.5 DB ON CONFLICT/UNIQUE
on normalized quote are NOT included — the current skip+flag behavior is safe,
whereas a UNIQUE on normalized_quote would fail on existing dups and a blind
merge risks losing provenance; they need their own chair-reviewed migration.
#82.6 over-merge guard is moot until merge lands. #81.6 full rhetorical-role
classifier deferred (section pre-filter + application flag cover the practical
case); #81.8 blocked on the human-tagged gold-set (harness now provided).

Verified:
- pytest tests/test_halacha_quality.py — 52 passed (14 new).
- calibrate: configured (0.55,0.70) → precision 1.0 (zero false-merge), recall
  0.30 — correct profile for an auto-approve-blocking signal.
- goldset export: 15-row sample CSV. batch reconcile: 819 halachot → 5
  cross-precedent candidate pairs.

Invariants: G1 (normalize at source — flag at insert, not at read); §6 (no
silent swallow — suspect items flagged to review, never dropped); G2 (no
parallel path — same store_halachot_for_chunk / compute_quality_flags).

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

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

@@ -592,10 +592,16 @@ async def _extract_impl(case_law_id: UUID, force: bool = False,
             flags = halacha_quality.compute_quality_flags(
                 coerced["rule_statement"], coerced["supporting_quote"],
                 coerced["reasoning_summary"], coerced["quote_verified"],
+                coerced["rule_type"],
             )
             coerced["quality_flags"] = flags
             if halacha_quality.FLAG_NON_DECISION in flags and coerced["rule_type"] != "obiter":
                 coerced["rule_type"] = "obiter"
+            # #81.4 — a binding-labeled rule that reads as a case-application is
+            # re-typed application (it carries FLAG_APPLICATION either way).
+            elif (halacha_quality.FLAG_APPLICATION in flags
+                  and coerced["rule_type"] == "binding"):
+                coerced["rule_type"] = "application"
             cleaned.append(coerced)
         # #81.3 NLI entailment — one batched judge call per chunk (fail-open).
         if config.HALACHA_NLI_ENABLED and cleaned: