feat: add HLS playback support with hls.js

- viewer.js: dynamic hls.js loading, HLS-aware panel creation, error handling
- schema.json: hlsManifest and mediaType fields (optional, backward compatible)
- types.ts: VideoEntry interface with MediaType type
- isHls() null guard fix
- tests: 39 tests (schema, viewer units, data flow, integration)
- CI: GitHub/Gitea Actions workflow (npm test on push/PR)
- deps: ajv, ajv-formats, jsdom for testing

src/types.ts

@@ -0,0 +1,74 @@
+/**
+ * Shared type definitions for the Goon Plugin.
+ *
+ * These types define the canonical video object shape used across:
+ * - chrome.storage.local (persistence layer)
+ * - Popup scan logic (index.js)
+ * - Viewer grid renderer (viewer.js)
+ *
+ * TypeScript project is configured (tsconfig.json) but source files
+ * are currently .js. The JSDoc-style interface below documents the
+ * contract; `tsc --noEmit` validates .js files against these types
+ * when @type references are used.
+ */
+
+/**
+ * Media delivery format of the video source.
+ * - 'direct' : plain MP4/WebM blob served via HTTP(S)
+ * - 'hls'    : HTTP Live Streaming manifest (.m3u8)
+ */
+export type MediaType = 'direct' | 'hls';
+
+/**
+ * A single video entry discovered by a tab scan.
+ *
+ * All fields except `url` are optional to preserve backward
+ * compatibility with entries written by older extension versions.
+ *
+ * @example
+ *   // Legacy entry (still valid)
+ *   { url: "https://example.com/video.mp4" }
+ *
+ * @example
+ *   // Full entry with HLS support
+ *   {
+ *     url: "https://example.com/playlist.m3u8",
+ *     src: "https://example.com/playlist.m3u8",
+ *     poster: "https://example.com/thumbnail.jpg",
+ *     tab: "Video Tab",
+ *     hlsManifest: "https://cdn.example.com/stream.m3u8",
+ *     mediaType: "hls"
+ *   }
+ */
+export interface VideoEntry {
+  /** Primary video URL. May point to the source file or the HLS manifest. */
+  url: string;
+
+  /** Direct source URL extracted from the <video> element (data-* or src). */
+  src?: string;
+
+  /** Poster / thumbnail image URL. */
+  poster?: string | null;
+
+  /** Title of the browser tab where the video was found. */
+  tab?: string;
+
+  /**
+   * URL to an HLS manifest (.m3u8).
+   *
+   * When present, the viewer loads Hls.js to play adaptive streams.
+   * Backward compatible: older entries simply omit this field.
+   */
+  hlsManifest?: string;
+
+  /**
+   * Media delivery format.
+   *
+   * Defaults to 'direct' when omitted. Set to 'hls' when the video
+   * is delivered via HTTP Live Streaming.
+   *
+   * Backward compatible: entries without this field are treated as
+   * `mediaType === 'direct'`.
+   */
+  mediaType?: MediaType;
+}