[Feature] Support OAuth 2.1 + PKCE for MCP servers, addable from dashboard

[rameshnetsys]

🎯 The Goal / Use Case

Let non-technical users add OAuth-protected MCP servers from the launcher dashboard by pasting a URL — same UX as Claude.ai's "Add connector." Works on cloud VMs with public URLs, no shell, no Node.js.

💡 Proposed Solution

Dashboard form to add an MCP by URL. Built-in OAuth 2.1 + PKCE with refresh token handling, reusing the launcher's own URL as the redirect URI so the browser flow completes inside the dashboard.

🚦 Impact & Roadmap Alignment

• This is a Core Feature
• This is a Nice-to-Have / Enhancement
• This aligns with the current Roadmap

🔄 Alternatives Considered

• skill.md + mcporter — works, but still requires shell access and skill authoring.Requires node, coping .mcporter/credentials.json
• mcp-remote as stdio bridge — works, but needs Node.js installed, and on headless/cloud VMs the OAuth callback is painful (port forwarding or curl tricks). Doing auth on desktop then copying ~/.mcp-auth/ to the server is possible but painful.