Add live Schemathesis contract gate

[yhay81]

What changed

• run deterministic Schemathesis coverage and positive fuzzing against live ASGI and Workerd servers
• isolate generated SQLite and D1 state from developer persistence
• keep multipart coverage while avoiding arbitrary multipart transport crashes in local Workerd
• tolerate npm 12 notices in the Pywrangler version probe
• verify the newly released Hayate 0.16.0 wheel and refresh compatibility evidence

Impact

The existing ASGI and Workerd CI flows now fail on typed OpenAPI contract regressions without polluting persistent local data.

Validation

• 29 passed, 1 skipped
• Ruff, SQL contracts, generated API, supply-chain checks
• ASGI: coverage 15/15 and fuzzing 111/111
• Workerd class/global: coverage 15/15 and fuzzing 111/111