Refine Inbound API: HTTP contract, extended types, logging, rate limiting

Define POST /api/{methodName} URL structure with X-API-Key header. Flat JSON
request/response with no envelope wrapper. Add extended type system (Object, List)
for complex API parameters and return values, applied to both Inbound API and
External System Gateway method definitions. Only failures logged; no rate limiting
in this controlled industrial environment.

Component-ExternalSystemGateway.md

@@ -41,8 +41,8 @@ Each external system definition includes:
   - Method name.
   - **HTTP method**: GET, POST, PUT, or DELETE.
   - **Path**: Relative path appended to the base URL (e.g., `/recipes/{id}`).
-  - Parameter definitions (name, type).
-  - Return type definition.
+  - Parameter definitions (name, type). Supports the extended type system (Boolean, Integer, Float, String, Object, List).
+  - Return type definition. Supports the extended type system for complex response structures.
 
 ## Database Connection Definition