feat(KB-221): rename CLI binary from kb to fn

- Rename binary from 'kb' to 'fn' in package.json bin entries
- Update package-config test to expect new binary name 'fn'
- Add changeset to track the binary rename for package consumers

packages/cli/package.json

@@ -6,7 +6,7 @@
     "pi-package"
   ],
   "bin": {
-    "kb": "./dist/bin.js"
+    "fn": "./dist/bin.js"
   },
   "pi": {
     "extensions": [