fix: terminate telemetry work on disposal

Give the best-effort telemetry adapter a terminal ACTIVE/DISPOSED lifecycle.
dispose() now removes the pagehide listener, clears the queue, invalidates
scheduled callback generations and aborts the in-flight sink; emit after
dispose is a no-op and a sink that ignores the abort cannot reschedule or
update post-dispose state. flush() joins the active delivery instead of
resolving early, and runtime infrastructure teardown disposes telemetry first.

Telemetry and diagnostics capacities are validated at construction against a
documented ceiling, so NaN or Infinity can no longer disable eviction.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

src/bootstrap/runtime-adapters.ts

@@ -480,6 +480,10 @@ export async function createRuntimeAdapters(
       crossContextInvalidationStatus: () =>
         serverStateGeneration.getSnapshot().crossContextStatus(),
       dispose() {
+        // N-04. Telemetry is torn down first: it must stop scheduling and
+        // delivering before the diagnostics and state dependencies it observes
+        // are destroyed.
+        telemetry.dispose();
         conditionalValidators.clear();
         serverStateScope.dispose();
         serverStateGeneration.dispose();