feat(go-services): Phase 2 ingest — shared Ingestor + shadow consumer

Implements the plugin event handlers (the /ws/position write logic) as a shared
Ingestor, validated against real traffic by replaying Python's /ws/live firehose
into an isolated dereth_go DB (no production write, no plugin stolen).

- ingest.go: faithful ports of telemetry (kill-delta -> char_stats, server
  received_at stamp), rare (rare_stats/rare_stats_sessions/rare_events), portal
  (coord upsert), character_stats (stats_data JSONB subset + upsert), spawn, and
  the memory-only handlers (vitals/quest/equipment_cantrip/nearby/dungeon). In
  -memory live state + read-side overlay accessors.
- shadow.go: coder/websocket consumer of /ws/live -> Ingestor.dispatch (telemetry
  matched by shape since its broadcast has no type field).
- main.go/store.go: ingest mode (READ_ONLY=false + SHADOW_INGEST_WS) wires the
  ingestor; read handlers (/character-stats, /equipment-cantrip, /quest-status)
  now consult the live overlay first, like Python.
- compose: shadow instance ingests ws://dereth-tracker:8765/ws/live.

Validated live: dereth_go has 73 distinct telemetry chars; shadow /live online
set == production (73=73); character_stats 5/5 exact byte-match (0 mismatch);
char_stats kill-deltas + portals accumulating. compare/compare_ingest.py.

Deferred to next pass: combat_stats (delta/merge), share_*, the /ws/position +
/ws/live servers (for cutover).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

go-services/tracker-go/main.go

@@ -39,6 +39,7 @@ type Server struct {
 	invProxy  *httputil.ReverseProxy
 	staticDir string
 	secretKey string
+	ingestor  *Ingestor // non-nil only in ingest/shadow mode
 	log       *slog.Logger
 }
 
@@ -93,6 +94,17 @@ func main() {
 			cancel()
 		}
 
+		// Shadow ingest: replay the Python /ws/live firehose into our handlers.
+		if cfg.IngestWS != "" {
+			if cfg.ReadOnly {
+				logger.Error("SHADOW_INGEST_WS set but READ_ONLY=true; refusing to ingest into the production DB")
+				os.Exit(1)
+			}
+			srv.ingestor = newIngestor(pool, logger, nil)
+			go srv.runShadowConsumer(ctx, cfg.IngestWS)
+			logger.Info("shadow ingest enabled", "source", cfg.IngestWS)
+		}
+
 		go srv.runCacheLoop(ctx)
 		go srv.runTotalsLoop(ctx)
 		logger.Info("db connected; cache loops started",