fix: prevent overlapping poll cycles in managers

Guarding polling re-entry avoids stacked async polls under slow responses, and unref on pending-call cleanup timer reduces idle wakeups.

src/hooks/comment-checker/pending-calls.test.ts

@@ -0,0 +1,38 @@
+import { describe, test, expect } from "bun:test"
+
+describe("pending-calls cleanup interval", () => {
+  test("starts cleanup once and unrefs timer", async () => {
+    //#given
+    const originalSetInterval = globalThis.setInterval
+    const setIntervalCalls: number[] = []
+    let unrefCalled = 0
+
+    globalThis.setInterval = ((
+      _handler: TimerHandler,
+      timeout?: number,
+      ..._args: any[]
+    ) => {
+      setIntervalCalls.push(timeout as number)
+      return {
+        unref: () => {
+          unrefCalled += 1
+        },
+      } as unknown as ReturnType<typeof setInterval>
+    }) as unknown as typeof setInterval
+
+    try {
+      const modulePath = new URL("./pending-calls.ts", import.meta.url).pathname
+      const pendingCallsModule = await import(`${modulePath}?pending-calls-test-once`)
+
+      //#when
+      pendingCallsModule.startPendingCallCleanup()
+      pendingCallsModule.startPendingCallCleanup()
+
+      //#then
+      expect(setIntervalCalls).toEqual([10_000])
+      expect(unrefCalled).toBe(1)
+    } finally {
+      globalThis.setInterval = originalSetInterval
+    }
+  })
+})