fix: resolve 13 review issues across casting components

- casting-player: remove redundant self-navigation useEffect
- casting-player: derive Type from metadata instead of hardcoding 'Movie'
- casting-player: pass null to useTrickplay instead of empty BaseItemDto
- casting-player: use != null for skip time labels (allow 0 to render)
- Chromecast: case-insensitive m3u8 detection via regex
- Chromecast: fix UUID hyphen indices to 4,6,8,10 for proper v4 format
- CastingMiniPlayer: use SeriesPrimaryImageTag for series poster URL
- ChromecastConnectionMenu: send rounded volume to castSession.setVolume
- ChromecastConnectionMenu: use isMutedRef in onValueChange to avoid stale closure
- ChromecastDeviceSheet: skip volume sync during active sliding
- ChromecastDeviceSheet: move unmute logic from onValueChange to onSlidingStart
- useCasting: detect playback start via isPlaying/playerState, not just progress>0
- useCasting: derive isChromecastAvailable from castState instead of hardcoding true
- useTrickplay: accept BaseItemDto|null with null guards on Id access

components/chromecast/ChromecastConnectionMenu.tsx

@@ -108,7 +108,7 @@ export const ChromecastConnectionMenu: React.FC<
 
       try {
         if (castSession) {
-          await castSession.setVolume(value / 100);
+          await castSession.setVolume(rounded / 100);
         }
       } catch (error) {
         console.error("[Connection Menu] Volume error:", error);
@@ -262,7 +262,9 @@ export const ChromecastConnectionMenu: React.FC<
                     onValueChange={async (value) => {
                       volumeValue.value = value;
                       handleVolumeChange(value);
-                      if (isMuted) {
+                      // Unmute when adjusting volume - use ref to avoid
+                      // stale closure and prevent repeated async calls
+                      if (isMutedRef.current) {
                         isMutedRef.current = false;
                         setIsMuted(false);
                         try {

components/chromecast/ChromecastDeviceSheet.tsx

@@ -45,7 +45,9 @@ export const ChromecastDeviceSheet: React.FC<ChromecastDeviceSheetProps> = ({
   const lastSetVolume = useRef(Math.round(volume * 100));
 
   // Sync volume slider with prop changes (updates from physical buttons)
+  // Skip updates while user is actively sliding to avoid overwriting drag
   useEffect(() => {
+    if (isSliding.current) return;
     volumeValue.value = volume * 100;
     setDisplayVolume(Math.round(volume * 100));
   }, [volume, volumeValue]);
@@ -275,13 +277,9 @@ export const ChromecastDeviceSheet: React.FC<ChromecastDeviceSheetProps> = ({
                         minimumTrackTintColor: isMuted ? "#666" : "#a855f7",
                         bubbleBackgroundColor: "#a855f7",
                       }}
-                      onSlidingStart={() => {
+                      onSlidingStart={async () => {
                         isSliding.current = true;
-                      }}
-                      onValueChange={async (value) => {
-                        volumeValue.value = value;
-                        handleVolumeChange(value);
-                        // Unmute when adjusting volume
+                        // Auto-unmute when user starts adjusting volume
                         if (isMuted && castSession) {
                           setIsMuted(false);
                           try {
@@ -292,6 +290,10 @@ export const ChromecastDeviceSheet: React.FC<ChromecastDeviceSheetProps> = ({
                           }
                         }
                       }}
+                      onValueChange={(value) => {
+                        volumeValue.value = value;
+                        handleVolumeChange(value);
+                      }}
                       onSlidingComplete={(value) => {
                         isSliding.current = false;
                         lastSetVolume.current = Math.round(value);