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/attic/root-history/ARCHITECTURE

@@ -750,7 +750,7 @@ async function apophisPlugin(fastify, options) {
 }
 
 module.exports = fp(apophisPlugin, {
-  name: 'apophis-fastify',
+  name: '@apophis/fastify',
   dependencies: ['@fastify/swagger']
 })
 ```
@@ -1879,7 +1879,7 @@ class ApophisSymbolicAnalyzer {
 ## File Structure
 
 ```
-apophis-fastify/
+@apophis/fastify/
 ├── lib/
 │   ├── formula-parser.js           # APOSTL formula parsing and evaluation
 │   ├── formula-substitutor.js      # Safe parameter substitution
@@ -1916,7 +1916,7 @@ apophis-fastify/
 const fastify = require('fastify')()
 
 // Register APOPHIS (registers @fastify/swagger automatically)
-await fastify.register(require('apophis-fastify'), {
+await fastify.register(require('@apophis/fastify'), {
   swagger: {
     openapi: '3.0.0',
     info: { title: 'Tournaments API', version: '1.0.0' }