chore: 2.1.0

Bumps the root package.json (and its lockfile entries) 2.0.0 -> 2.1.0
for the v2.1.0 milestone release.

Only the ROOT manifest carries a version -- the four clients/* packages
deliberately have none, since the Inspector ships as one tarball with a
single version number that every Node client resolves through
readInspectorVersion() in core/node/version.ts. So this is the only
file that needs changing.

Done with `npm version 2.1.0 --no-git-tag-version`: the tag is NOT
created here. #1903 merges as a merge commit, so this commit lands on
main intact and the release tag is pushed against it after the merge.
Creating the tag now would point it at a commit that is not yet on the
release branch.

The publish job asserts the release tag matches this version.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YAt8rqxysNbhYWLhoRm3fU

Author: cliffhall

package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "@modelcontextprotocol/inspector",
-  "version": "2.0.0",
+  "version": "2.1.0",
   "description": "The Model Context Protocol Inspector",
   "keywords": [
     "MCP",