refactor(thumbnail): [PKG-TOOL-THUMB-04] type runtime modules and retain emitter attribution

refactor/third-party.json

@@ -1025,6 +1025,39 @@
           "sha256": "e00bbf82bf08c452825690372ded39a9b60f4baf438f0e7ce8300e9bc4629c03"
         }
       ]
+    },
+    {
+      "id": "thumbnail-tiny-emitter",
+      "riskId": "VENDOR-09",
+      "inputs": [
+        "packages/artplayer-tool-thumbnail/src/emitter.ts"
+      ],
+      "owners": [
+        "PKG-TOOL-THUMB-04",
+        "PKG-TOOL-THUMB-06"
+      ],
+      "sourceStatus": "Local on/once/emit/off structurally correspond to the fixed tiny-emitter 2.1.0 reference; recovered 3.5.31 declared ^2.1.0. Exact original copied revision is unknown. This migration adds types while preserving the local class and dispatch behavior.",
+      "licenseStatus": "Pinned upstream MIT notice copied verbatim into package THIRD_PARTY_NOTICES and included by the normal standalone build banner. Final packed distribution verification remains 06.",
+      "upstreamSources": [
+        "https://raw.githubusercontent.com/scottcorgan/tiny-emitter/2.1.0/index.js",
+        "https://raw.githubusercontent.com/scottcorgan/tiny-emitter/2.1.0/LICENSE",
+        "https://raw.githubusercontent.com/scottcorgan/tiny-emitter/2.1.0/package.json"
+      ],
+      "upstreamReviewedAt": "2026-09-13",
+      "updatePolicy": "Keep attribution and pinned upstream comparison. Review observable dispatch changes independently from type migration; run upstream/historical/candidate parity tests and validate all bundle and packed notices.",
+      "fingerprints": [
+        {
+          "path": "packages/artplayer-tool-thumbnail/src/emitter.ts",
+          "algorithm": "sha256-lf",
+          "sha256": "2844fa8d279d35d676f61eef4f8a3e173146548c64b8e49f2dabfc25aec56668"
+        }
+      ],
+      "reviewEvidence": [
+        "refactor/baselines/thumbnail-vendor/sources.json",
+        "test/thumbnail-runtime.test.js",
+        "test/thumbnail-vendor.test.js",
+        "refactor/changes/2026-09-13-PKG-TOOL-THUMB-04-runtime-types.md"
+      ]
     }
   ],
   "integrations": [