Replace per-request subprocess spawning with a single long-lived duckdb
Python connection (in-memory + ATTACH read-only). LOAD httpfs and S3 auth
are paid once at startup; object cache accumulates across requests.
Benchmarked improvement on remote: Q1 10x, Q2 3x, Q3 9x, Q4 22x faster.
Add duckdb==1.5.1 Python package to Dockerfile.
- swap DuckDB UI for ttyd web terminal (--writable, -readonly db)
- add POST /query endpoint with X-Password auth for curl-based SQL execution
- fix UTF-8 rendering: set LANG/LC_ALL=C.UTF-8 in container
- pass BUCKET_REGION env var for correct S3 signing region
- simplify start.sh: drop Xvfb, views.duckdb generation, blocking duckdb -ui
- add less, ncurses-bin to Dockerfile for proper pager/terminal support
- update Caddyfile: single route to ttyd with flush_interval -1 for websocket
- update README to reflect current architecture and document /query usage
- remove duckdb-ui.service, schemas.json, file_tree.md (generated artifacts)
