Add Vynix plugin (MCP server)

[Surajsharma07]

What this PR does

Adds a new plugin: Vynix — a Model Context Protocol server that gives AI coding agents access to Vynix visual website feedback, bug reports, screenshots, and AI diagnosis.

• Plugin name: vynix
• Type: remote source
• Source URL + pinned SHA: https://github.com/UseVynix/vynix-mcp.git @ dc173bae17f6096d2dbc6456f0d1dd27237f9626
• Homepage: https://www.vynix.in/

Ownership

• I own this plugin or have the right to distribute it.
• The source repo is published under our official org (UseVynix/vynix-mcp).

Checklist

• Added exactly one entry in .grok-plugin/marketplace.json (valid JSON, kebab-case name).
• Remote source pins a full 40-char lowercase commit sha, public + reachable.
• Regenerated .grok-plugin/plugin-index.json (python3 scripts/generate-plugin-index.py).
• python3 scripts/validate-catalog.py passes locally.
• python3 scripts/generate-plugin-index.py --check passes locally.
• homepage + clear description set.
• License is stated (MIT).

Security

• No curl | bash, remote-code download/exec, or postinstall RCE.
• No reading/exfiltration of secrets, tokens, .env, or env vars. The server only reads its own declared config env vars (VYNIX_API_TOKEN, etc.) to authenticate to the Vynix API.
• Hooks and MCP scope are least-privilege. Scoped tools only; no shell-exec tool.
• Network endpoints this plugin calls (and why):
  • https://www.vynix.in — Vynix REST API (projects, annotations, screenshots, diagnosis, comments, issues).
  • https://mcp.vynix.in/mcp — optional hosted streamable-http transport.
• Credentials/permissions it requires (and why): VYNIX_API_TOKEN, a personal access token generated at https://www.vynix.in/mcp, used to authenticate the agent to the user's own Vynix account. Optional email/password env vars support token-refresh mode.

Notes for reviewers

Source is published under our official org UseVynix. This PR is opened from a maintainer's personal fork (Surajsharma07), who is an admin of the UseVynix org. The plugin ships one MCP server (npm @usevynix/mcp-server, stdio via npx, plus an optional hosted remote). keywords/domains are intentionally brand-scoped.