feat(third_party): add Meltwater plugin

[minupalaniappan]

Summary

• Add Meltwater as a third_party/ marketplace plugin, in the Attio (Add Attio third-party MCP plugin #339) / Hunter (Add Hunter third-party MCP plugin (API key header auth) #340) shape.
• One of nine hosted-MCP connectors that grok.com offers publicly (GrowthBook visibility all) and the Cursor marketplace does not. The server URL matches Grok's production connector_catalog.mcp_server_url.
• Registers the plugin in .cursor-plugin/marketplace.json and the root README table.
• Based on main; bottom of the stack now that feat(third_party): add Gamma plugin #347, feat(third_party): add Webull plugin #348, feat(third_party): add S&P Global plugin #349, feat(third_party): add Interactive Brokers plugin #350 have merged.

Endpoint	https://api.meltwater.com/v2/mcp
Auth	OAuth with dynamic client registration. Probed: 401 → app.meltwater.com, registration_endpoint present.
Grok visibility	all

MCP

{
  "mcpServers": {
    "meltwater": {
      "type": "http",
      "url": "https://api.meltwater.com/v2/mcp"
    }
  }
}

Stack

Split from #345 into one PR per plugin. Independent plugins come first; the two with external prerequisites (Coinbase, BigQuery) are last so they never block the others.

1. gamma feat(third_party): add Gamma plugin #347 ✅ merged
2. webull feat(third_party): add Webull plugin #348 ✅ merged
3. sp-global feat(third_party): add S&P Global plugin #349 ✅ merged
4. interactive-brokers feat(third_party): add Interactive Brokers plugin #350 ✅ merged
   5. meltwater feat(third_party): add Meltwater plugin #351 ← this PR
5. daloopa feat(third_party): add Daloopa plugin #352
6. excalidraw feat(third_party): add Excalidraw plugin #353
7. coinbase feat(third_party): add Coinbase plugin #354
8. google-cloud-bigquery feat(third_party): add Google Cloud BigQuery plugin #355

Test plan

• node scripts/validate-plugins.mjs passes on this branch
• Endpoint probed for OAuth discoverability and dynamic client registration; the auth shape above is what the server actually supports
• README has Install / MCP / Before you connect / What agents can do / Notes / Docs / License, with capabilities sourced from vendor docs
• marketplace.json, plugin.json, and README table descriptions are identical
• Logo visually reviewed at 192×192
• Install from Cursor Settings → Plugins, complete sign-in, and smoke test listing saved searches

Notes

• Meltwater's public docs still describe API-key auth, but the server advertises standard MCP OAuth with DCR, so this is a plain URL entry.
• Requires the Meltwater MCP package on the subscription; available tools depend on the products in it.

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Note

Low Risk
Marketplace metadata and a new hosted-MCP connector package only; no changes to core app logic or shared auth infrastructure.

Overview
Adds a new Meltwater third-party marketplace plugin so Cursor agents can search media/social mentions and pull analytics via Meltwater’s hosted MCP at https://api.meltwater.com/v2/mcp.

The change registers meltwater in .cursor-plugin/marketplace.json and the root README plugin table, and introduces third_party/meltwater/ with plugin.json, mcp.json (HTTP MCP, OAuth sign-in—no API key in config), README, CHANGELOG, and MIT license.

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