feat: add Meta Threads MCP integration to setup wizard

[chinkan]

Summary

Add Meta Threads publishing support to RustFox via the baguskto/threads-mcp MCP server. This includes a new catalog entry in the setup wizard, an interactive setup guide modal matching the existing Google Workspace pattern, and documentation updates.

Changes

• setup/index.html

  • Added threads entry to MCP_CATALOG under new "Social Media" category with npx threads-mcp-server runner and THREADS_ACCESS_TOKEN environment variable
  • Added #threads-modal HTML with 4-step token setup guide (create Meta app, add Threads API product, configure permissions, generate long-lived token)
  • Implemented openThreadsModal() and closeThreadsModal() JavaScript functions following the existing OAuth modal pattern
  • Extended Escape key handler to close Threads modal
  • Wired __THREADS_GUIDE_BUTTON__ token in catalog renderer to trigger modal

• config.example.toml

  • Added commented example block for Threads MCP server with token setup instructions and configuration template

• README.md

  • Added Threads row to Popular MCP Servers table
  • Added Threads TOML configuration example to Examples section

Implementation Details

• No Rust source changes required; RustFox's existing MCP manager handles stdio-based servers generically
• Modal reuses existing CSS classes (.modal-overlay, .oauth-steps, .oauth-warning, etc.) for consistency
• Token setup guide covers all required permissions: threads_basic, threads_content_publish, threads_manage_replies, threads_read_replies
• Includes warning about 60-day token expiry and refresh instructions

https://claude.ai/code/session_01DCLwWCFMP9cutqAPqjJTAC