refactor: audit fixes — clean up bugs, dead code, and type mismatches

- viewer.js: remove undefined state.segmentsBuffered assignment in BUFFER_RESET
- viewer.js: add missing 'switching' and 'ended' phases to PHASE_ICONS
- index.js: remove redundant Strategy B3 (duplicated B1 video-element walk)
- index.js: filter standard <video> DOM attributes from custom-property scans
  (m3u8DeepProbeFn B1 and scrapeFn Priority 3) to avoid iterating built-in
  properties that can never contain HLS data
- background.js: remove unconditional return true (handlers are synchronous)
  and remove dead error-response for unknown message types
- types.ts: align MediaType union ('direct' | 'hls') with actual runtime
  value used in code ('video' | 'hls')
- package.json: remove hls.js from dependencies (loaded from CDN at runtime,
  never imported as an npm module)

src/viewer/index.js

@@ -171,8 +171,23 @@ function m3u8DeepProbeFn() {
   // NOT a reverse-lookup. It returns its input unchanged — Hls.cast(video) just
   // returns the <video> element with no .url property. Real players store the
   // HLS instance directly on the video element as a custom property.
+  // Only check non-standard properties (skip built-in <video> attributes).
+  const STANDARD_VIDEO_ATTRS = new Set([
+    'src', 'srcObject', 'crossOrigin', 'preload', 'autoplay', 'muted',
+    'defaultMuted', 'loop', 'controls', 'controlsList', 'disableRemotePlayback',
+    'volume', 'playbackRate', 'defaultPlaybackRate', 'playbackState',
+    'currentTime', 'startTime', 'duration', 'buffered', 'seekable',
+    'played', 'seeking', 'ended', 'readyState', 'networkState',
+    'videoWidth', 'videoHeight', 'error', 'textTracks', 'videoTracks',
+    'audioTracks', 'loadingBeganAt', 'label', 'id', 'className',
+    'classList', 'style', 'attributes', 'dataset', 'innerHTML', 'textContent',
+    'outerHTML', 'outerText', 'slot', 'accessKey', 'draggable', 'hidden',
+    'lang', 'spellcheck', 'tabIndex', 'title', 'translate',
+    'width', 'height', 'poster', 'preload', 'referrerPolicy',
+  ]);
   for (const v of document.querySelectorAll('video')) {
     for (const key of Object.keys(v)) {
+      if (STANDARD_VIDEO_ATTRS.has(key)) continue;
       const obj = v[key];
       if (!obj || typeof obj !== 'object') continue;
       // Check for common HLS instance patterns on video elements
@@ -193,23 +208,6 @@ function m3u8DeepProbeFn() {
     }
   }
 
-  // B3: Fallback — walk video element keys looking for HLS-related objects
-  for (const v of document.querySelectorAll('video')) {
-    for (const key of Object.keys(v)) {
-      if (key.toLowerCase().includes('hls') || key === 'player') {
-        const hlsObj = v[key];
-        if (hlsObj && typeof hlsObj === 'object') {
-          for (const subKey of Object.keys(hlsObj)) {
-            if (typeof hlsObj[subKey] === 'string' && hlsObj[subKey].includes('.m3u8')) {
-              if (!seen.has(hlsObj[subKey])) { seen.add(hlsObj[subKey]); manifests.push({ url: hlsObj[subKey], player: `video.${key}.${subKey}` }); }
-            }
-          }
-          walk(hlsObj, `video.${key}`, 0);
-        }
-      }
-    }
-  }
-
   // Strategy C: Inline scripts
   for (const script of document.querySelectorAll('script:not([src])')) {
     const text = script.textContent || '';
@@ -281,11 +279,24 @@ function scrapeFn(hlsManifests) {
         mediaType = 'hls';
         src = hlsManifest;
       }
-      // Priority 3: Scan video element properties for HLS instance references.
-      // Hls.cast() is a TypeScript identity cast in hls.js — NOT a reverse-lookup.
-      // Real players store the HLS instance on the video element as custom properties.
+      // Priority 3: Scan video element custom properties for HLS instance references.
+      // Only check non-standard (custom) properties — skip built-in <video> attrs.
       if (!hlsManifest) {
+        const stdAttrs = new Set([
+          'src', 'srcObject', 'crossOrigin', 'preload', 'autoplay', 'muted',
+          'defaultMuted', 'loop', 'controls', 'controlsList', 'disableRemotePlayback',
+          'volume', 'playbackRate', 'defaultPlaybackRate', 'playbackState',
+          'currentTime', 'startTime', 'duration', 'buffered', 'seekable',
+          'played', 'seeking', 'ended', 'readyState', 'networkState',
+          'videoWidth', 'videoHeight', 'error', 'textTracks', 'videoTracks',
+          'audioTracks', 'loadingBeganAt', 'label', 'id', 'className',
+          'classList', 'style', 'attributes', 'dataset', 'innerHTML', 'textContent',
+          'outerHTML', 'outerText', 'slot', 'accessKey', 'draggable', 'hidden',
+          'lang', 'spellcheck', 'tabIndex', 'title', 'translate',
+          'width', 'height', 'poster', 'referrerPolicy',
+        ]);
         for (const key of Object.keys(v)) {
+          if (stdAttrs.has(key)) continue;
           const obj = v[key];
           if (obj && typeof obj === 'object' && typeof obj.url === 'string') {
             const u = obj.url.toLowerCase();

src/viewer/viewer.js

@@ -170,7 +170,9 @@ const PHASE_ICONS = {
   loading: '\u2B07',    // down arrow
   buffering: '\u27F7',  // spinning
   playing: '\u25B6',    // play
+  switching: '\u21BB',  // right arrow corner
   error: '\u2717',      // X
+  ended: '\u23F9',      // stop
 };
 
 /**
@@ -413,7 +415,6 @@ function wireHlsEvents(hls, video, panel) {
     state.lastActivity = Date.now();
     state.bufferedAhead = 0;
     state.segmentsLoaded = 0;
-    state.segmentsBuffered = 0;
     renderPanelState(video, panel);
   });