Refactor MCP mock server configuration and update tests for OAuth support

- Removed the old `mcp-mock-server` service and replaced it with `mock-mcp` in both `docker-compose` files.
- Updated health check and dependencies to reflect the new service name.
- Modified E2E test configurations to use the new `mock-mcp` service URL.
- Added a minimal mock MCP server implementation with OAuth support for testing.
- Updated feature tests to check for OAuth authentication requirements and response headers.

Author: jrobertboos

tests/e2e/configuration/server-mode/lightspeed-stack.yaml

@@ -21,6 +21,6 @@ authentication:
 mcp_servers:
   - name: "mcp-oauth"
     provider_id: "model-context-protocol"
-    url: "http://localhost:3000"
+    url: "http://mock-mcp:3000"
     authorization_headers:
       Authorization: "oauth"

tests/e2e/mock_mcp_server/server.py

@@ -44,14 +44,14 @@ def _json_response(self, data: dict) -> None:
         self.wfile.write(body)
 
     def do_GET(self) -> None:  # pylint: disable=invalid-name
-        """OAuth probe: always 401 with WWW-Authenticate."""
+        """Handle GET requests."""
         if self.path == "/health":
             self._json_response({"status": "ok"})
         else:
             self._require_oauth()
 
     def do_POST(self) -> None:  # pylint: disable=invalid-name
-        """MCP JSON-RPC: 401 without valid Bearer; 200 with minimal responses otherwise."""
+        """Handle POST requests."""
         if self._parse_auth() is None:
             self._require_oauth()
             return