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/case-studies/overview.md

@@ -0,0 +1,17 @@
+# Case studies
+
+Five verified case studies, each reproducible from a pinned corpus through
+the same gated pipeline, each number carrying its 95% CI and workload.
+
+- [tokei — compounding algorithmic wins (Rust)](./tokei.md) — three class-5
+  wins on the same hot function, each unattended and audited.
+- [Cheap wins first: build flags & allocators](./build-flags.md) — LTO
+  accepted (+10%), mimalloc held for a human ruling then accepted-scoped.
+- [The caught false-accept (comrak)](./comrak-false-accept.md) — the
+  leaking teardown the bench loved, overturned by audit. The most important
+  study.
+- [cJSON — the cross-language proof (C)](./cjson.md) — a sub-threshold win
+  rejected, then a byte-identical win accepted, on a C target.
+- [Services & scale: latency under load](./service.md) — the cJSON win
+  measured as a latency delta under coordinated-omission-correct replay,
+  turned into a dollar figure mechanically.