fix(realtime): reset stable-flag React state on options change; de-vacuous blip test

Address Greptile review:
- useStableFlag: reset React state to the fresh controller's baseline when
  the controller is recreated on an options change, so a dynamic consumer
  changing delayMs/minVisibleMs while active with value already false can no
  longer strand the flag at true.
- test: read the live probe.active getter in the blip test instead of a
  destructured snapshot, which was bound to false at destructure time and
  made the assertion vacuous.

Author: waleedlatif1

apps/sim/hooks/use-stable-flag.test.ts

@@ -38,15 +38,15 @@ describe('createStableFlagController', () => {
   })
 
   it('suppresses a blip that heals before the delay (flash-on)', () => {
-    const { controller, states, active } = setup()
+    const probe = setup()
 
-    controller.setValue(true)
+    probe.controller.setValue(true)
     vi.advanceTimersByTime(DELAY_MS - 1)
-    controller.setValue(false)
+    probe.controller.setValue(false)
     vi.advanceTimersByTime(10_000)
 
-    expect(states).toEqual([])
-    expect(active).toBe(false)
+    expect(probe.states).toEqual([])
+    expect(probe.active).toBe(false)
   })
 
   it('does not turn on one tick before the delay boundary', () => {

apps/sim/hooks/use-stable-flag.ts

@@ -106,6 +106,12 @@ export function useStableFlag(value: boolean, options: StableFlagOptions = {}):
   const controllerRef = useRef<ReturnType<typeof createStableFlagController> | null>(null)
 
   useEffect(() => {
+    // Reset to the fresh controller's baseline. Without this, recreating the
+    // controller on an options change while `active` is true and `value` is
+    // already false would strand the React state at true — the new controller
+    // starts internally false, so its `setValue(false)` early-returns and never
+    // emits `onChange(false)`.
+    setActive(false)
     const controller = createStableFlagController(setActive, { delayMs, minVisibleMs })
     controllerRef.current = controller
     controller.setValue(valueRef.current)