feat(go-services): inventory-go Phase A — read-side scaffold + simple endpoints

First slice of the inventory-service port, running in parallel READ-ONLY against
the production inventory_db (never written):
- main.go/store.go: pgx pool (forced read-only), enum-DB loader extracting
  AttributeSetInfo for set-name resolution, /health, /sets/list, /characters/list.
- Dockerfile + compose service inventory-go (127.0.0.1:8772, enum JSON mounted).

Validated vs the Python service on the same DB: /characters/list 167 chars exact
counts; /sets/list 76 sets EXACT match (ids, names, counts).

Remaining (large): /search/items (40+ filters + enrich_db_item), inventory
fetch, item-processing ingestion (extract_item_properties), and the suitbuilder
solver.

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

go-services/docker-compose.go.yml

@@ -124,5 +124,33 @@ services:
         max-size: "10m"
         max-file: "3"
 
+  # Go port of inventory-service. Phase A: read side, READ-ONLY against the
+  # production inventory_db, validated vs the Python service. Loopback :8772.
+  inventory-go:
+    build:
+      context: ./go-services/inventory-go
+      args:
+        BUILD_VERSION: ${BUILD_VERSION:-dev}
+    image: inventory-go:local
+    container_name: inventory-go
+    ports:
+      - "127.0.0.1:8772:8772"
+    environment:
+      PORT: "8772"
+      DATABASE_URL: "postgresql://inventory_user:${INVENTORY_DB_PASSWORD}@inventory-db:5432/inventory_db"
+      READ_ONLY: "true"
+      ENUM_DB_PATH: "/enums/comprehensive_enum_database_v2.json"
+      LOG_LEVEL: "INFO"
+    volumes:
+      - ./inventory-service/comprehensive_enum_database_v2.json:/enums/comprehensive_enum_database_v2.json:ro
+    depends_on:
+      - inventory-db
+    restart: unless-stopped
+    logging:
+      driver: "json-file"
+      options:
+        max-size: "10m"
+        max-file: "3"
+
 volumes:
   dereth-go-data: