mcp: resolve openapi.json from env/in-repo/same-dir so a standalone copy works

mcp/shopdb_mcp.py

@@ -34,7 +34,15 @@ from fastmcp import FastMCP
 from fastmcp.server.openapi import MCPType, RouteMap
 
 _HERE = os.path.dirname(os.path.abspath(__file__))
-_SPEC = os.path.join(_HERE, '..', 'docs', 'openapi.json')
+# Find the OpenAPI spec: explicit env, the in-repo docs/, or next to this script
+# (so a standalone copy of mcp/ with openapi.json beside it just works).
+_SPEC_CANDIDATES = [
+    os.environ.get('SHOPDB_OPENAPI'),
+    os.path.join(_HERE, '..', 'docs', 'openapi.json'),
+    os.path.join(_HERE, 'openapi.json'),
+]
+_SPEC = next((p for p in _SPEC_CANDIDATES if p and os.path.isfile(p)),
+             _SPEC_CANDIDATES[1])
 
 BASE = os.environ.get('SHOPDB_BASE',
                       'https://tsgwp00525.wjs.geaerospace.net/shopdb')