chore: add system docs, specs, and misc updates from other sessions

- Add complete docs/systems/ reference (18 system docs)
- Add federation relay status doc and prior spec/plan docs
- Remove superseded docs/federation-dm-s2s.md (replaced by docs/systems/federation.md)
- CLAUDE.md updates
- Minor fixes in social.ts, types.ts, AddDmMemberModal, NewDmModal, UserSettings

packages/web/src/components/modals/UserSettings.tsx

@@ -109,6 +109,7 @@ export function UserSettingsModal() {
               name={user?.displayName || user?.username || ''}
               size={36}
               userId={user?.id}
+              avatarColor={user?.avatarColor}
             />
             <div className="min-w-0">
               <div className="text-sm font-medium text-txt-primary truncate">{user?.displayName || user?.username}</div>
@@ -160,6 +161,7 @@ export function UserSettingsModal() {
                 name={user?.displayName || user?.username || ''}
                 size={36}
                 userId={user?.id}
+                avatarColor={user?.avatarColor}
               />
               <div className="min-w-0">
                 <div className="text-sm font-medium text-txt-primary truncate">{user?.displayName || user?.username}</div>