docs: reposition README — Charter as ecosystem entrypoint

- Lead with "Your first CF Workers project shouldn't take a week"
- Add ecosystem packages table (llm-providers, worker-observability, audit-chain)
- Integrate ADF as a feature, not an afterthought
- Cut from 420 to 204 lines — removed self-governance example, exhaustive
  command reference, semver policy, research section
- Grouped commands by intent (Build / Govern / ADF)
- Added attribution

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: Kurt Overmier