v0.3.0 — SQL Query Mode

New in v0.3.0

POST /query/sql — Full SQL via DuckDB + pfc extension

Optional SQL mode for users with DuckDB installed on the gateway server.
Standard /query still works without any DuckDB dependency.

• sql_mode: true/false in health response
• HTTP 503 with clear message if DuckDB not installed
• Full DuckDB SQL: GROUP BY, AVG, JOINs, window functions
• Same NDJSON output format as /query

See CHANGELOG.md for full details.