feat: add comments and cleanup unused imports across codebase

static/player/types.ts

@@ -1,38 +1,45 @@
+// stream source for a single mode (sub/dub)
 export interface ModeSource {
   token: string;
   subtitles: SubtitleItem[];
   qualities?: string[];
 }
 
+// subtitle track from backend
 export interface SubtitleItem {
   lang: string;
   token: string;
 }
 
+// skip segment (intro/outro) from backend data attribute
 export interface SkipSegment {
-  type: string;
+  type: string; // 'op' or 'ed'
   start: number;
   end: number;
 }
 
+// parsed subtitle cue from VTT
 export interface SubtitleCue {
   start: number;
   end: number;
   text: string;
 }
 
+// loaded subtitle track for UI
 export interface SubtitleTrack {
   lang: string;
   label: string;
   url: string;
 }
 
+// validated skip segment within video bounds
 export interface ActiveSegment {
   type: string;
   start: number;
   end: number;
 }
 
+// timeline range (handles seekable ranges in live streams)
 export interface TimelineBounds {
   start: number;
   end: number;