feat: use json editor instead of <string,string> pairs in metadata tab

[Izelude]

Summary

Replaced the <string, string> pairs in the Metadata Tab with a json editor (<string, string> pairs are often not enough for complex metadata). added a Pretty Button for convenience.

i needed this change for my usecases which required complex json meta.

Type of Change

• New feature (non-breaking change that adds functionality)

Changes Made

Metadata Tab ui changed to a Json Editor.
Before:

After:

Testing

• Tested in UI mode
• Tested with Streamable HTTP transport
• Added/updated automated tests
• Manual testing performed

Test Results and/or Instructions

No issues.

Checklist

• Code follows the style guidelines (ran npm run prettier-fix)
• Self-review completed

Breaking Changes

not a breaking change, already persisted metadata will correctly be transformed to json.

Additional Context

I had this change for a while but my original fork was reforked from a different fork of the inspector so i only now found time to refork from here and open a PR.
Been using this for at least 3 months from my own repo, if its not needed here in the official feel free to close the PR, i'm fine using my own forked version :)

[cliffhall]

Closing: v1 is deprecated.

Thank you for this contribution, and apologies for the long wait for a response.

v1 will receive security fixes only. We reviewed every open v1 PR for security impact before closing — see the backlog triage in #1819 — and a small number were retained for a final 1.0.5 patch release. This one is a functionality, compatibility, or cleanup change rather than a vulnerability fix, so it is being closed unmerged. This is not a judgment on the quality of the work — it's a consequence of the branch it targets being frozen.

If the underlying problem still exists in v2, we'd genuinely like to know. Please open an issue describing it against v2. Note that we accept external contributions as issues rather than pull requests — maintainers handle design and implementation through a prompt-driven workflow. See CONTRIBUTORS.md.

Thanks again for taking the time to contribute to the Inspector.