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

__tests__/run.mjs

@@ -0,0 +1,11 @@
+/**
+ * Test entry point — imports all test suites then runs them.
+ */
+import './schema.test.mjs';
+import './viewer_units.test.mjs';
+import './data_flow.test.mjs';
+import './viewer_integration.test.mjs';
+import { run } from './runner.mjs';
+
+const result = await run();
+process.exit(result.totalFailed > 0 ? 1 : 0);