docs: full mdBook site + GitHub Pages deploy; rewrite README as project front page

- docs/: an mdBook documentation site — thesis, architecture, measurement
  discipline, equivalence gates, agent loop, isolation/anti-reward-hacking,
  playbook, ROI, reproduce, roadmap, and the five case studies (pulled from
  their single source in results/ via {{#include}}). Builds clean (21
  pages).
- .github/workflows/docs.yml: builds mdBook and deploys to GitHub Pages on
  push to main (one-time setup: Settings → Pages → Source = GitHub Actions).
- README.md: rewritten as the project front page — the thesis, the verified
  results table, layout, quick start, how it stays honest, links to the
  book. Replaces the stale Phase-0-era text.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EcKPWQ3MQD4NdEHwar96u2

docs/src/SUMMARY.md

@@ -0,0 +1,27 @@
+# Summary
+
+[hotpath](./introduction.md)
+
+- [The thesis: trust is the product](./thesis.md)
+- [Architecture](./architecture.md)
+- [Measurement discipline](./measurement.md)
+- [Equivalence gates](./equivalence.md)
+- [The agent loop](./agent-loop.md)
+- [Isolation & anti-reward-hacking](./isolation.md)
+- [The playbook](./playbook.md)
+- [ROI: from stopwatch to dollars](./roi.md)
+
+# Case studies
+
+- [Overview](./case-studies/overview.md)
+- [tokei — compounding algorithmic wins (Rust)](./case-studies/tokei.md)
+- [Cheap wins first: build flags & allocators](./case-studies/build-flags.md)
+- [The caught false-accept (comrak)](./case-studies/comrak-false-accept.md)
+- [cJSON — the cross-language proof (C)](./case-studies/cjson.md)
+- [Services & scale: latency under load](./case-studies/service.md)
+
+# Reference
+
+- [Reproduce it yourself](./reproduce.md)
+- [The trust boundary (infra)](./infra.md)
+- [Roadmap & scope](./roadmap.md)