fix(deps): bump undici override to ^6.28.0

Resolves open Dependabot alerts #16, #17, #18 (moderate). The undici
copy is transitive (@cursor/sdk -> @connectrpc/connect-node), so it is
pinned via the existing overrides block, matching the tar/esbuild
override-floor pattern.

Author: justin-carper

package-lock.json

@@ -63,7 +63,7 @@
     "semver": "^7.8.4"
   },
   "overrides": {
-    "undici": "^6.24.0",
+    "undici": "^6.28.0",
     "tar": "^7.5.11",
     "node-gyp": "^12.4.0",
     "esbuild": "^0.28.1"