fix: make Ctrl+C cancel ObjC semaphore waits within ~1s

semaphore_wait_with_timeout now polls photos_cancelled every second
instead of blocking for the full timeout duration

bridge/photokit_bridge.m

@@ -10,8 +10,15 @@ static NSDictionary *make_error_dict(NSString *message) {
 }
 
 static BOOL semaphore_wait_with_timeout(dispatch_semaphore_t sem, int64_t seconds) {
-    dispatch_time_t timeout = dispatch_time(DISPATCH_TIME_NOW, seconds * NSEC_PER_SEC);
-    return dispatch_semaphore_wait(sem, timeout) == 0;
+    int64_t deadline = (int64_t)[NSDate timeIntervalSinceReferenceDate] + seconds;
+    while (1) {
+        if (photos_cancelled) return NO;
+        int64_t remaining = deadline - (int64_t)[NSDate timeIntervalSinceReferenceDate];
+        if (remaining <= 0) return NO;
+        int64_t waitSecs = remaining < 1 ? remaining : 1;
+        dispatch_time_t timeout = dispatch_time(DISPATCH_TIME_NOW, waitSecs * NSEC_PER_SEC);
+        if (dispatch_semaphore_wait(sem, timeout) == 0) return YES;
+    }
 }
 
 static NSDictionary *collection_to_dict(PHCollection *collection) {