Note: This PR was re-created from #3103 due to repository maintenance. Your code and branch are intact. @omorros please verify everything looks good.

🔗 Related Issue

Closes #3085

📝 Summary

The Manage Members modal loaded all non-members eagerly via infinite scroll, which crashed browsers at 20K+ users due to DOM accumulation.

Changes:

• Non-members section no longer loads on modal open. Users must search by name/email first; results are capped at 50.
• Current members section gains its own search bar with server-side filtering via a new search parameter on get_team_members().
• The old monolithic client-side search function (serverSideUserSearch) is replaced by two focused server-side search functions (serverSideMemberSearch, serverSideNonMemberSearch).

🏷️ Type of Change

• Bug fix

🧪 Verification

✅ Checklist

• Code formatted (make black isort pre-commit)
• Tests added/updated for changes
• Documentation updated (if applicable)
• No secrets or credentials committed

📓 Notes (optional)

Files changed (4):

• mcpgateway/admin.py — Split unified search into two per-section inputs; non-members container no longer auto-loads
• mcpgateway/services/team_management_service.py — Added search param + _escape_like() to get_team_members()
• mcpgateway/static/admin.js — Replaced serverSideUserSearch with serverSideMemberSearch and serverSideNonMemberSearch
• tests/unit/mcpgateway/test_admin.py — Updated 13 tests for new search param, added test_admin_team_non_members_partial_html_empty_search