[Jmmt-mingrui]

Summary

• remove the preferred/optional semantic routing configuration
• stop loading semantic workspaces during normal MCP authentication
• load semantics only when semantic tools or the Semantic Web UI are used
• keep read-only SQL, Doris search, and health checks independent of semantic loading
• update the query guide, README, and regression tests

Validation

• 251 unit tests passed
• offline test suite passed
• Python compile check passed
• live-server integration tests were not run because localhost:3000 was not running