feat(casting): unify Chromecast and AirPlay into single casting interface

BREAKING CHANGE: Merged separate Chromecast and AirPlay implementations into unified casting system

- Created unified casting types and helpers (utils/casting/)
- Built useCasting hook that manages both protocols
- Single CastingMiniPlayer component works with both Chromecast and AirPlay
- Single casting-player modal for full-screen controls
- Protocol-aware UI: Red for Chromecast, Blue for AirPlay
- Shows device type icon (TV for Chromecast, Apple logo for AirPlay)
- Detects active protocol automatically
- Previous separate implementations (ChromecastMiniPlayer, AirPlayMiniPlayer) superseded

Benefits:
- Better UX: One cast button shows all available devices
- Cleaner architecture: Protocol differences abstracted
- Easier maintenance: Single UI codebase
- Protocol-specific logic isolated in adapters

utils/casting/types.ts

@@ -0,0 +1,87 @@
+/**
+ * Unified Casting Types and Options
+ * Abstracts Chromecast and AirPlay into a common interface
+ */
+
+export type CastProtocol = "chromecast" | "airplay";
+
+export interface CastDevice {
+  id: string;
+  name: string;
+  protocol: CastProtocol;
+  type?: string;
+}
+
+export interface CastPlayerState {
+  isConnected: boolean;
+  isPlaying: boolean;
+  currentItem: any | null;
+  currentDevice: CastDevice | null;
+  protocol: CastProtocol | null;
+  progress: number;
+  duration: number;
+  volume: number;
+  showControls: boolean;
+  isBuffering: boolean;
+}
+
+export interface CastSegmentData {
+  intro: { start: number; end: number } | null;
+  credits: { start: number; end: number } | null;
+  recap: { start: number; end: number } | null;
+  commercial: Array<{ start: number; end: number }>;
+  preview: Array<{ start: number; end: number }>;
+}
+
+export interface AudioTrack {
+  index: number;
+  language: string;
+  codec: string;
+  displayTitle: string;
+}
+
+export interface SubtitleTrack {
+  index: number;
+  language: string;
+  codec: string;
+  displayTitle: string;
+  isForced: boolean;
+}
+
+export interface MediaSource {
+  id: string;
+  name: string;
+  bitrate?: number;
+  container: string;
+}
+
+export const CASTING_CONSTANTS = {
+  POSTER_WIDTH: 300,
+  POSTER_HEIGHT: 450,
+  ANIMATION_DURATION: 300,
+  CONTROL_HIDE_DELAY: 5000,
+  PROGRESS_UPDATE_INTERVAL: 1000,
+  SEEK_FORWARD_SECONDS: 10,
+  SEEK_BACKWARD_SECONDS: 10,
+} as const;
+
+export const DEFAULT_CAST_STATE: CastPlayerState = {
+  isConnected: false,
+  isPlaying: false,
+  currentItem: null,
+  currentDevice: null,
+  protocol: null,
+  progress: 0,
+  duration: 0,
+  volume: 0.5,
+  showControls: true,
+  isBuffering: false,
+};
+
+export type ConnectionQuality = "excellent" | "good" | "fair" | "poor";
+
+// Protocol-specific colors for UI differentiation
+export const PROTOCOL_COLORS = {
+  chromecast: "#e50914", // Red (Google Cast)
+  airplay: "#007AFF", // Blue (Apple)
+} as const;