docs: add paper citations, fix pedagogical issues, improve SKILL.md

- Cite arxiv 2602.23922 (Invariant-Driven Automated Testing) in all major docs
- Add Progressive Complexity section to SKILL.md for LLM guidance
- Fix SKILL.md Fast Start example to use deterministic ID generation
- Fix getting-started.md failure output inconsistency
- Fix auth-patterns.md TypeScript syntax in JS doc
- Fix fastify-structure.md Date.now() in test helper
- Fix observe.md misleading workspace heading
- Build: clean | Tests: 849 pass, 0 fail

docs/getting-started.md

@@ -2,6 +2,8 @@
 
 Get from install to your first behavioral bug in 10 minutes.
 
+APOPHIS is inspired by [Invariant-Driven Automated Testing](https://arxiv.org/abs/2602.23922) (Malhado Ribeiro, 2021): instead of only validating request and response shape, encode intended behavior as executable contracts and let the tool find violations automatically.
+
 ## Prerequisites
 
 - Node.js 20.x or 22.x
@@ -70,7 +72,7 @@ Expected
   response_code(GET /users/{response_body(this).id}) == 200
 
 Observed
-  GET /users/usr-123 returned 404
+  GET /users/usr-7d865e returned 404
 
 Why this matters
   The resource created by POST /users is not retrievable.