Add release pipeline: launchd runtime, deploy scripts, release workflow

[selfcontained]

Summary

• bin/install-launchd — clones repo to ~/.dispatch/server/, builds, installs launchd service; --port flag for running on a custom port (e.g. --port 6767)
• bin/uninstall-launchd — unloads and removes plist
• bin/dispatch-deploy <tag|--latest> — deploys a verified tag to the server directory, reloads launchd, health checks; auto-rollback to previous tag on failure with detailed failure log at ~/.dispatch/logs/last-release-failure.log
• bin/dispatch-release <patch|minor|major> — triggers GitHub Actions release workflow, waits, reads produced tag, calls dispatch-deploy; spawns diagnosis agent on workflow failure (not deploy failure, since Dispatch may be down then)
• .github/workflows/release.yml — manual workflow_dispatch with version input; runs full CI, bumps both package.json files, commits, tags, pushes, creates GitHub Release
• DISPATCH_PORT replaces PORT as primary env var (PORT kept as fallback)
• docker-compose.yml — rename hostess-postgres → dispatch-postgres (applied during migration, not automatically)
• src/config.ts — reads DISPATCH_PORT first, updated hostess defaults to dispatch

Migration plan (after merge)

1. bin/install-launchd --port 6767 — starts new launchd instance alongside existing tmux instance
2. Verify on port 6767
3. pg_dump from hostess-postgres
4. Start dispatch-postgres on 5433, restore dump
5. Update ~/.dispatch/server/.env DATABASE_URL to dispatch on 5433, reload launchd
6. Stop hostess-postgres, move dispatch to 5432, reload
7. Stop tmux instance whenever ready

Test plan

• CI passes on this PR
• bin/install-launchd --port 6767 starts successfully
• Health check passes on 6767
• Agent spawned from 6767 instance has full tool access

🤖 Generated with Claude Code