docs: add project README and document radar workflow

[DaNN-55]

What changed

• Add a project README describing Razer-Raders, its evidence-first AI Radar workflow, self-hosted deployment model, and current MVP scope.
• Document Docker Compose startup, local development, Ollama and OpenAI-compatible runtime configuration, administration, testing, and project structure.
• Include the existing local commit that changes Brief collection and publication to 09:00 and 17:00 (Asia/Shanghai).

Why

The repository did not have a project README. The new documentation makes the current product boundary and the verified deployment path discoverable to contributors and self-hosters.

Validation

• git diff --check
• pnpm lint
• pnpm test — 101 tests passed
• pnpm build