Registration canonicalizes usernames to lowercase (auth.ts:32),
but the friend-request endpoint compared with strict eq() against
raw user input, so 'Bob' returned 404 even when 'bob' existed.
Trim and lowercase before lookup, matching the rest of the auth
boundary. Empty-after-trim now returns 400 (was: 404).
Tests appended to social.test.ts as a second describe block
sharing the harness from Task 1.
Tombstoned users, replicated federated stubs, and users with
discoverable=0 were all surfacing in Add Friend search results.
Add the three WHERE filters that /api/social/discover already
applies. Federated users continue to be surfaced via the
client-side cross-instance fan-out in socialStore.searchUsers.
New tests: social.test.ts covers all five filter cases plus
existing self-exclusion and displayName-match behaviours.
Jannis Braun