Faster team roster lookups

Loading a workspace no longer scans the full team list to confirm you are a member. The membership check is now a single indexed row fetch, and the team page loads in one round trip.

A small change with a real impact on perceived speed for workspaces with large rosters.

Membership verification uses an indexed `LIMIT 1` lookup instead of iterating the team

The team settings page makes one query for the full roster and derives membership in memory, instead of two round trips

Tested against rosters up to several hundred members; the page now loads in well under a second on cold cache