fix(query): refetch on remount after mutation while unmounted [#2986]

[viniciusdacal]

Closes #2986.

Summary

• MutationEventBus now tracks a monotonic per-entity-type version that increments on every emit(); getVersion(entityType) exposes it.
• MemoryCache.set(key, value, version?) records the stamp; CacheStore<T> gained an optional getVersion(key).
• query() stamps every cache write with the bus version for its entity type and skips cache hits whose stamp is older than the current bus version. SSR-hydrated entries are explicitly stamped 0 so a client emit that lands before hydration completes correctly marks the SSR payload stale on remount. Nav-prefetch cache-hit paths (init-time and effect-time) honor the same check, using the descriptor's _entity when the query's entityMeta hasn't been assigned yet.

Why

Navigating list → form → back via router.navigate() left the list showing pre-mutation data until a full page reload. The list query had unsubscribed from the bus on navigate-away, so the emit() fired by the form's mutation reached no live listener — yet the cached entry and its query indices remained and were served on remount. emit() only notified live subscribers; it didn't touch the cache.

Public API Changes

• MutationEventBus.getVersion(entityType: string): number — new.
• CacheStore<T>.set(key, value, version?) — added optional version parameter (backward compatible).
• CacheStore<T>.getVersion(key): number | undefined — new optional method. Custom cache implementations without it keep the previous behavior.

No breaking changes. Entity-backed queries automatically participate. Non-entity queries are unaffected.

Test plan

• vtz test — 2481 tests pass in @vertz/ui
• vtz test — 1285 tests pass in @vertz/ui-server
• vtz run typecheck — clean
• vtzx oxlint — no new warnings (16 pre-existing, 16 after)
• vtzx oxfmt --check — clean
• New regression tests in packages/ui/src/query/__tests__/query.test.ts:
  • Direct descriptor: mount → dispose → emit same type → remount → fresh fetch
  • Descriptor-in-thunk: same flow, with lazy entity metadata
  • Custom key: same flow
  • Cross-entity isolation: emit on unrelated type → cache still served
• New unit tests in packages/ui/src/query/__tests__/cache.test.ts (version stamp: set/get/delete/clear/LRU/v0)
• New unit tests in packages/ui/src/store/__tests__/mutation-event-bus.test.ts (getVersion: initial state, increments per type, reset on clear)

Pre-existing out-of-scope note

The effect calls raw._fetch() eagerly on every run before the cache-hit check is evaluated. On a cache hit the resulting promise is suppressed via .catch, but the fetch call itself has already started. Worth revisiting separately — unrelated to this fix.