feat: Docker distribution — Dockerfile + compose with opencode

[StatPan]

Closes #4

What

• Dockerfile — multi-stage build (builder → runner). Produces a minimal image with only dist/ + prod dependencies.
• docker-compose.yml — two modes:
  • docker compose up agentree — agentree only (connect to existing opencode)
  • docker compose --profile with-opencode up — full stack (opencode + agentree)
• .dockerignore — excludes node_modules, dist, .env, .git, docs, assets
• README.md — added Docker section under Quick start

Why

Users who prefer containers can run agentree without Node.js installed. The with-opencode profile handles the "I don't have opencode yet" case.

Test plan

• pnpm test passes
• pnpm exec tsc --noEmit passes
• pnpm exec tsc --noEmit -p tsconfig.client.json passes
• docker compose build agentree builds successfully
• docker compose --profile with-opencode up starts both services

[gemini-code-assist]

Code Review

This pull request introduces Docker support by adding a multi-stage Dockerfile, a docker-compose configuration, and updated documentation in the README. The review feedback highlights a critical bug where missing migration files in the runner stage would cause the application to fail at startup, and suggests improvements for container security and service orchestration reliability.

[gemini-code-assist]

The application requires the drizzle folder to run database migrations at startup (as seen in src/server/cli.ts). Since the runner stage only copies the dist folder, the migrations will fail. You should copy the migrations folder from the builder stage.

COPY --from=builder /app/dist ./dist
COPY --from=builder /app/drizzle ./drizzle

[gemini-code-assist]

It is a security best practice to run Docker containers as a non-root user. The node image provides a built-in node user that can be used for this purpose. Ensure that the /app directory and any mounted volumes have the correct permissions for this user.

FROM node:20-alpine AS runner
RUN corepack enable
WORKDIR /app
USER node

[gemini-code-assist]

When using the with-opencode profile, the agentree service should wait for the opencode service to be healthy before starting. This prevents agentree from exiting immediately if it cannot connect to opencode during the initial boot sequence.

  agentree:
    build: .
    depends_on:
      opencode:
        condition: service_healthy
        required: false