containerize with Haloy: Dockerfile, Caddy basicauth, haloy.yml for db.xn--2dk.xyz

- Dockerfile: debian slim, installs DuckDB CLI, Python deps, Caddy
- start.sh: runs prepara_db.py → starts Caddy (basicauth) → starts DuckDB UI
- Caddyfile: updated for container (no TLS, port 8080, Haloy handles HTTPS)
- haloy.yml: deploys to db.xn--2dk.xyz on port 8080
- requirements.txt: duckdb, boto3, python-dotenv
- prepara_db.py, open_gui.sh, duckdb-ui.service: add previously untracked files
- remove prepara_gui.py (replaced by prepara_db.py)

start.sh

@@ -0,0 +1,11 @@
+#!/bin/bash
+set -euo pipefail
+
+echo "[start] Building DuckDB views from S3..."
+python3 prepara_db.py
+
+echo "[start] Starting Caddy..."
+caddy start --config /app/Caddyfile --adapter caddyfile
+
+echo "[start] Starting DuckDB UI on :4213..."
+exec duckdb --ui basedosdados3.duckdb