feat: add Docker deployment and Gitea Actions CI/CD

Add multi-stage Dockerfile, docker-compose with persistent volumes,
and Gitea Actions workflows for CI (lint/test/build) and releases
(tag, Docker image push, changelog). Support DATABASE_PATH env var
for configurable SQLite location to enable proper volume mounting.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

entrypoint.sh

@@ -0,0 +1,4 @@
+#!/bin/sh
+set -e
+bun run db:push
+exec bun run src/server/index.ts