F2 SLICE-5: @vscode/test-electron host E2E (create→reload→re-anchor→orphan) (#4)

Drives the extension's returned ThreadController API + asserts the on-disk
sidecar and rendered Comments state (spec §6.8 fallback). All 4 host tests
green against VS Code 1.124.0.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

package.json

@@ -52,15 +52,21 @@
     "watch": "node esbuild.mjs --watch",
     "typecheck": "tsc --noEmit",
     "test": "vitest run",
+    "pretest:e2e": "npm run build && tsc -p tsconfig.e2e.json",
+    "test:e2e": "node ./out/test/e2e/runTest.js",
     "vscode:prepublish": "node esbuild.mjs"
   },
   "dependencies": {
     "@cline/sdk": "0.0.46"
   },
   "devDependencies": {
+    "@types/mocha": "^10.0.7",
     "@types/node": "^22.0.0",
     "@types/vscode": "^1.90.0",
+    "@vscode/test-electron": "^2.4.0",
     "esbuild": "^0.23.0",
+    "glob": "^11.0.0",
+    "mocha": "^10.7.0",
     "typescript": "^5.5.0",
     "vitest": "^2.0.0"
   }