Support revalidate = false for App route segment config

[NathanDrake2406]

Summary

Vinext currently ignores non-numeric App route segment revalidate exports while resolving effective segment config. Next.js accepts export const revalidate = false to mean cache indefinitely (effectively Infinity).

This is a pre-existing parity gap, but PR #993 makes it more visible because layout/page segment config is now reduced across the full route tree.

Expected behavior

• A route whose only segment config is revalidate = false should produce an explicit indefinite-cache policy rather than null/unset.
• Mixed segment configs should preserve shortest-wins semantics: numeric intervals should win over false because any finite interval is shorter than Infinity.

Current behavior

resolveRevalidateSeconds() ignores false, so revalidate = false alone is indistinguishable from no segment config.

Notes

This likely needs a cache-layer representation for indefinite caching that is distinct from "unset" before the resolver can model this cleanly.