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>

.gitea/workflows/ci.yml

@@ -0,0 +1,28 @@
+name: CI
+
+on:
+  push:
+    branches: [develop]
+  pull_request:
+    branches: [develop]
+
+jobs:
+  ci:
+    runs-on: docker
+    container:
+      image: oven/bun:1
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Install dependencies
+        run: bun install --frozen-lockfile
+
+      - name: Lint
+        run: bun run lint
+
+      - name: Test
+        run: bun test
+
+      - name: Build
+        run: bun run build