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>

tests/unit/runtime-adapters.test.ts

@@ -138,6 +138,38 @@ describe("runtime adapter composition", () => {
     adapters.infrastructure.dispose();
   });
 
+  it("runtime infrastructure disposal disposes telemetry first", async () => {
+    const fetcher = vi.fn(async () => new Response(null, { status: 204 }));
+    const adapters = await createRuntimeAdapters({
+      runtime: {
+        ...runtime,
+        config: {
+          ...runtime.config,
+          TELEMETRY_ENABLED: true,
+          TELEMETRY_ENDPOINT: "https://telemetry.test/events",
+        },
+      } as Runtime,
+      release,
+      host: {},
+      fetcher: fetcher as unknown as typeof fetch,
+    });
+
+    adapters.outputPorts.telemetry.emit("api.request.failed", {
+      error_kind: "SERVER_FAILURE",
+      http_status_group: "5xx",
+      attempt_count_bucket: "1",
+      route_id: "TEST_ROUTE",
+    });
+    expect(adapters.outputPorts.telemetry.pendingCount()).toBe(1);
+
+    adapters.infrastructure.dispose();
+
+    expect(adapters.outputPorts.telemetry.pendingCount()).toBe(0);
+    await Promise.resolve();
+    await Promise.resolve();
+    expect(fetcher).not.toHaveBeenCalled();
+  });
+
   it("replaces the QueryClient and coordinator for each session generation", async () => {
     const adapters = await createRuntimeAdapters({ runtime, release, host: {} });
     const previousClient = adapters.infrastructure.queryClient;