fix: harden engine, enrich failure diagnostics, close adoption gaps

- P0: CLI verify now honors  test budget with seeded multi-sample
- P0: Observe sampling enforced via Math.random() gate in hook-validator
- P1: Remove misleading undici-mock-agent isolation option
- P1: Qualify reuses shared discoverRouteDetails() with warnings
- P1: Chaos/scenario config exposed via preset schema
- P1: README/docs limitations updated to current state
- P2: Nested response annotations prefer 2xx deterministically
- P2: --changed documented as heuristic in verify.md

- Add observe sink tests (sampling 0/1, sink failure non-interference)
- Add verify runs regression tests (scale, determinism, variants)
- Add configured-scenario qualify test (independent of OAuth fixture)
- Add coverageBreakdown to qualify artifacts (per-gate route coverage)
- Add production-style observe example with real sink in docs/observe.md
- Add nightly/staging vs PR gating guidance to docs/qualify.md

- Enrich VerifyFailure with formula-aware diagnostics:
  status:201 => 'HTTP 200', body field checks => actual values
- Remove stale observe CLI activation message
- Document outbound mocks as process-global in getting-started.md
- Refresh APOPHIS_ADOPTION_AUDIT.md with current state

903 tests pass, build clean, typecheck clean.

docs/llm-safe-adoption.md

@@ -2,7 +2,7 @@
 
 APOPHIS is designed to be safe and predictable for LLM-generated Fastify services.
 
-It applies the invariant-driven approach from [Invariant-Driven Automated Testing](https://arxiv.org/abs/2602.23922) (Malhado Ribeiro, 2021) to LLM-assisted development: constrained vocabulary, deterministic replay, and executable contracts give coding agents a verifiable loop between generated changes and behavioral correctness.
+It applies an invariant-driven approach to LLM-assisted development: constrained vocabulary, deterministic replay, and executable contracts give coding agents a verifiable loop between generated changes and behavioral correctness.
 
 ## Why APOPHIS Is Good for LLM-Generated Services
 
@@ -164,7 +164,7 @@ console.log(verifyResult);
 2. **Run doctor first**: Catch setup issues before running verify.
 3. **Use `--changed` in CI**: Only verify routes that changed in the PR.
 4. **Commit config**: Store `apophis.config.js` in version control.
-5. **Pin versions**: Pin `apophis-fastify` version in `package.json`.
+5. **Pin versions**: Pin `@apophis/fastify` version in `package.json`.
 
 ## Troubleshooting