feat(go-services): inventory-go Phase C — ingestion (validated, isolated DB)

Wires the validated item-processor into the ingestion endpoints, writing to an
isolated inventory-go-db (never production):
- schema.go: faithful 7-table replica of inventory-service/database.py.
- ingest.go: /process-inventory (full replace), POST/DELETE single item, with the
  exact delete-then-insert flow, dynamic INSERT builder (quotes reserved "unique"),
  spell union (is_active), and item_raw_data verbatim. enhancements always inserts.
- compose: isolated inventory-go-db (postgres:14, 127.0.0.1:5435) + read-write
  inventory-go-shadow (:8773) that owns it; schema init on boot.

Validated by ingesting a recently-ingested character's items (from production's
original_json) into the shadow DB and diffing vs production: byte-identical —
items 243, combat 243, enhancements 243, ratings 6, requirements 19, spells 52
all match; 0 per-column mismatches across 243 items.

Finding: older production normalized rows can be STALE (predate the code reading
Decal keys 218103832/218103835); Go matches the CURRENT Python code, so validate
ingestion against recently-ingested characters.

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

go-services/inventory-go/main.go

@@ -71,12 +71,24 @@ func main() {
 	defer pool.Close()
 	srv.pool = pool
 
+	// Ingest mode owns its DB: create the schema on first run.
+	if !readOnly {
+		sctx, c := context.WithTimeout(ctx, 60*time.Second)
+		initSchema(sctx, pool, logger)
+		c()
+	}
+
 	mux := http.NewServeMux()
 	mux.HandleFunc("GET /health", srv.handleHealth)
 	mux.HandleFunc("GET /sets/list", srv.handleSetsList)
 	mux.HandleFunc("GET /characters/list", srv.handleCharactersList)
 	mux.HandleFunc("GET /search/items", srv.handleSearchItems)
 	mux.HandleFunc("POST /debug/process", srv.handleDebugProcess)
+	// Ingestion (works in read-write mode; on the read-only prod instance these
+	// fail the read-only transaction, which is the intended guard).
+	mux.HandleFunc("POST /process-inventory", srv.handleProcessInventory)
+	mux.HandleFunc("POST /inventory/{character_name}/item", srv.handleUpsertItem)
+	mux.HandleFunc("DELETE /inventory/{character_name}/item/{item_id}", srv.handleDeleteItem)
 
 	httpSrv := &http.Server{Addr: addr, Handler: withLogging(mux), ReadHeaderTimeout: 10 * time.Second}
 	go func() {