Available MCP Servers: quick-link accounts from warning state and details view

[ObnoxiousProxy]

• Motivation:
  Reduce friction by allowing users to link accounts directly when an account is missing.

• Proposed solution:
  In frontend/src/app/(dashboard)/available-mcp-servers/page.tsx, expose a clear action to open AddAccountDialog wherever a no-account warning appears; also provide a link from each server’s details view/modal.

• Additional context:

  • Hooks: frontend/src/features/connected-accounts/hooks/use-connected-account.tsx.