Chore: harden A2UI bundle dependency resolution (#22507)

Merged via /review-pr -> /prepare-pr -> /merge-pr.

Prepared head SHA: d84c5bde51
Co-authored-by: vincentkoc <25068+vincentkoc@users.noreply.github.com>
Co-authored-by: obviyus <22031114+obviyus@users.noreply.github.com>
Reviewed-by: @obviyus

package.json

@@ -174,6 +174,7 @@
     "json5": "^2.2.3",
     "jszip": "^3.10.1",
     "linkedom": "^0.18.12",
+    "long": "^5.3.2",
     "markdown-it": "^14.1.1",
     "node-edge-tts": "^1.2.10",
     "opusscript": "^0.0.8",
@@ -192,6 +193,8 @@
   },
   "devDependencies": {
     "@grammyjs/types": "^3.24.0",
+    "@lit-labs/signals": "^0.1.3",
+    "@lit/context": "^1.1.6",
     "@types/express": "^5.0.6",
     "@types/markdown-it": "^14.1.2",
     "@types/node": "^25.3.0",
@@ -199,9 +202,11 @@
     "@types/ws": "^8.18.1",
     "@typescript/native-preview": "7.0.0-dev.20260219.1",
     "@vitest/coverage-v8": "^4.0.18",
+    "lit": "^3.3.2",
     "oxfmt": "0.33.0",
     "oxlint": "^1.48.0",
     "oxlint-tsgolint": "^0.14.1",
+    "signal-utils": "0.21.1",
     "tsdown": "^0.20.3",
     "tsx": "^4.21.0",
     "typescript": "^5.9.3",