feat(docker): add containerized deployment

[iagorobo24-hub]

Description

Adds Docker support for running OpenCode Telegram Bot as a container.

This is submitted separately from #209 as requested.

What changed

• adds a multi-stage Docker image with application code and production
  dependencies built into the image;
• runs the bot as a non-root user with dumb-init;
• persists runtime state under /app/data;
• adds a Docker Compose configuration;
• keeps OpenCode as an external dependency configured through
  OPENCODE_API_URL;
• adds Docker usage documentation.

Design notes

• secrets and .env are not copied into the image;
• source code, dist, and node_modules are not bind-mounted from the host;
• no Docker healthcheck is added because the bot does not currently expose
  its own health endpoint;
• port 4096 is not exposed by the bot image because it belongs to the
  OpenCode server.
• Networking limitation: The provided docker-compose.yml uses
  network_mode: host because OpenCode by default binds to
  127.0.0.1:4096 only. This allows the container to reach the OpenCode
  server on the host without additional configuration.
  • Linux: network_mode: host works natively.
  • macOS/Windows (Docker Desktop 4.34+): host networking is supported when enabled in Settings → "Enable host networking".
  • If host networking is not available or not enabled, OpenCode must be configured to listen on 0.0.0.0 or a reachable IP, and OPENCODE_API_URL set accordingly.

Validation

• clean Docker build: PASS
• better-sqlite3 loads inside the container: PASS
• Docker Compose config validation: PASS
• lint: PASS
• typecheck: PASS
• build: PASS
• tests: BASELINE_HANG_CONFIRMED (same pre-existing wizard hang on upstream main)