feat(manifold): add matcher versioning to separate legacy accepted matches from v3_outcome_guard metrics

Add MANIFOLD_MATCHER_VERSION="v3_outcome_guard" tag persisted to
manifold_match_audit.matcher_version so metrics can isolate current-matcher
stats from pre-versioning records, whose accepted matches the outcome
guard would now reject.

- schema: add matcher_version column + index; idempotent startup backfill
  tagging NULL rows as legacy_pre_outcome_guard (no outcome types) or
  v2_outcome_guard_no_version (has outcome type, version not persisted)
- save_manifold_audit: write matcher_version on every new record
- get_manifold_matches: split summary into current_version / all_time /
  legacy; recent_matches now carry matcher_version

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

bot/data/schema.sql

@@ -220,6 +220,36 @@ CREATE INDEX IF NOT EXISTS idx_mfld_audit_poly_mkt  ON manifold_match_audit(poly
 ALTER TABLE manifold_match_audit ADD COLUMN IF NOT EXISTS poly_outcome_type TEXT;
 ALTER TABLE manifold_match_audit ADD COLUMN IF NOT EXISTS mfld_outcome_type TEXT;
 
+-- ─────────────────────────────────────────────────────────────────────────────
+-- Matcher versioning — separate current-matcher metrics from legacy records
+--
+-- matcher_version tags each audit row with the matcher that produced it
+-- (MANIFOLD_MATCHER_VERSION in bot/data/manifold.py).  This lets the metrics
+-- endpoint isolate current_version stats from pre-versioning records, whose
+-- accepted matches would now be rejected by the outcome-compatibility guard.
+--
+-- Backfill is one-shot and idempotent (only touches NULL matcher_version rows):
+--   * rows with no outcome types  → 'legacy_pre_outcome_guard' (pre outcome-guard;
+--     accepted without any outcome-type validation)
+--   * rows with an outcome type   → 'v2_outcome_guard_no_version' (existed between
+--     the outcome-guard and this versioning; real version not persisted)
+-- We tag rather than infer the exact version that wasn't recorded.
+-- ─────────────────────────────────────────────────────────────────────────────
+ALTER TABLE manifold_match_audit ADD COLUMN IF NOT EXISTS matcher_version TEXT;
+
+UPDATE manifold_match_audit
+SET matcher_version = 'legacy_pre_outcome_guard'
+WHERE matcher_version IS NULL
+  AND poly_outcome_type IS NULL
+  AND mfld_outcome_type IS NULL;
+
+UPDATE manifold_match_audit
+SET matcher_version = 'v2_outcome_guard_no_version'
+WHERE matcher_version IS NULL
+  AND (poly_outcome_type IS NOT NULL OR mfld_outcome_type IS NOT NULL);
+
+CREATE INDEX IF NOT EXISTS idx_mfld_audit_version ON manifold_match_audit(matcher_version);
+
 -- ─────────────────────────────────────────────────────────────────────────────
 -- Metric exclusion — administrative closure flag
 --