feat(KB-330): rename internal packages from @kb/* to @fusion/*

- Rename @kb/core, @kb/dashboard, @kb/engine to @fusion/* namespace
- Update all import statements across 143+ files to use new package names
- Update workspace dependencies and root package.json references
- Fix bundler configurations (tsup, vite) for new package names
- Update test files and fix typecheck issues
- Add changeset file documenting the package rename

packages/dashboard/package.json

@@ -1,5 +1,5 @@
 {
-  "name": "@kb/dashboard",
+  "name": "@fusion/dashboard",
   "version": "0.1.0",
   "type": "module",
   "exports": {
@@ -35,8 +35,8 @@
     "@codemirror/state": "^6.5.2",
     "@codemirror/theme-one-dark": "^6.1.2",
     "@codemirror/view": "^6.36.4",
-    "@kb/core": "workspace:*",
-    "@kb/engine": "workspace:*",
+    "@fusion/core": "workspace:*",
+    "@fusion/engine": "workspace:*",
     "@types/multer": "^2.1.0",
     "@xterm/xterm": "^5.5.0",
     "@xterm/addon-fit": "^0.10.0",