perf(routing): enforce or auto-enable compiled route snapshot for production hot path #75

Context

Lock-free route matching depends on compiled snapshot (freeze()). If app is not frozen, request path still uses mutex-backed routers, reducing scalability.

Goal

Make compiled routing harder to miss in production.

Options

• Auto-freeze/auto-compile on first request.
• Strong runtime warning when serving without compiled routers.
• Explicit config to enforce freeze-before-serve.

Acceptance criteria

• Clear strategy implemented (auto-freeze or enforced guard).
• Behavior documented in routing/perf docs.
• No regressions in route registration lifecycle tests.

Notes

Prefer minimal surprise for existing users; avoid breaking dev ergonomics.