Kann Mattermost Professional weg?

Build a personal replacement for Mattermost Professional in an empty repository.
Use Next.js 15, TypeScript, PostgreSQL, Drizzle ORM, WebSockets, and Docker Compose; do not offer alternative stacks.
The core loop is: self-host private team chat with channels, threads, search, and integrations, and keep membership and moderation under the owner's control.
Make the first run work locally with one documented command.
Store all user data locally by default and make export straightforward.
Put secrets in .env, ship .env.example, and never commit credentials.
Implement spaces, channels, topics, replies, reactions, mentions, profiles, roles, and invitations.
Use WebSockets for live updates but preserve every message transactionally in PostgreSQL.
Add moderation queues, reports, blocks, rate limits, attachment limits, and an audit log.
Provide email digests, browser notifications, search, pinned content, and member export.
Add owner-controlled retention, account deletion, backup, restore, and health checks.
Ship Docker Compose with a seeded demo, migrations, and an emergency admin command.
Include clear empty, loading, success, and recoverable error states.
Add input validation, safe filenames, and graceful handling of unavailable APIs.
Write focused tests for the core transformation and one end-to-end happy path.
Create a README with setup, architecture, permissions, data location, and backup steps.
Do not add accounts, billing, telemetry, analytics, or a hosted control plane.
Deliberately leave out public-network discovery and existing member liquidity.
Deliberately leave out production voice or video rooms.
Deliberately leave out native mobile applications, enterprise SSO, and 24-hour abuse operations.
Finish by running the tests and listing the exact commands used.