fix: example app uses deterministic ID generation; trim dead exports

- Fix examples/app/src/routes/users.ts to use crypto hash instead of Date.now()
- Remove unused renderProgress export from human.ts
- Remove unused formatTripleBoundaryCounterexample from triple-boundary-testing.ts
- Remove unused clearCapturedRoutes from discovery.ts
- Remove dead BUILTIN_PLUGIN_CONTRACTS constant
- Build: clean | Tests: 847 pass, 2 fail (pre-existing flaky --changed tests)

examples/app/src/routes/users.ts

@@ -1,3 +1,4 @@
+import crypto from 'crypto'
 import type { FastifyInstance } from 'fastify'
 
 export async function userRoutes(fastify: FastifyInstance) {
@@ -30,7 +31,7 @@ export async function userRoutes(fastify: FastifyInstance) {
     },
   }, async (req, reply) => {
     const { name, email } = req.body as { name: string; email: string }
-    const id = `user-${Date.now()}`
+    const id = `user-${crypto.createHash('sha256').update(email).digest('hex').slice(0, 8)}`
     const user = { id, name, email }
     fastify.db.users.set(id, user)
     reply.status(201)