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/manifold.py

@@ -33,6 +33,12 @@ from typing import Optional
 
 import httpx
 
+# Version tag for every audit record this matcher produces. Persisted to
+# manifold_match_audit.matcher_version so metrics can isolate current-version
+# stats from legacy/pre-versioning records. Do NOT change this value once set;
+# bump to a new string only when matcher semantics change materially.
+MANIFOLD_MATCHER_VERSION = "v3_outcome_guard"
+
 MANIFOLD_API = "https://api.manifold.markets/v0"
 CACHE_TTL_SEC = 1800  # 30 minutes