docs(phase-4): add docs-code consistency tests and final polish

[S1M0N38]

Part of #224 — v2 docs rewrite (Diátaxis).

Goal

Drift-proofing + final QA before merge.

Tasks

• Add tests/cli/test_docs.py (openrpc ↔ api.md, typer ↔ cli.md, config env vars ↔ cli.md, link checker)
• Update llmstxt config + regenerate llms.txt / llms-full.txt; verify with an LLM client
• Run make format + make quality; fix mdformat issues
• Full docs review pass: every page read for tone consistency (Diátaxis: no quadrant mixing)

Dependencies

• Blocked by: docs(phase-1): rewrite reference pages (api, cli, configuration) #226 (Phase 1 — reference), docs(phase-3): write how-to guides (install, launch, instances, write-a-bot, contribute) #228 (Phase 3 — how-to)
• Blocks: Phase 5 (ship)

Done when

• CI green with the new docs test
• llms.txt regenerated and LLM-verified
• Zero mdformat/quality failures