Feat v0.6.15 user display audit (#50)

Co-authored-by: Jeffrey Smith <jasafpro@gmail.com>
Co-committed-by: Jeffrey Smith <jasafpro@gmail.com>

server/store/interfaces.go

@@ -103,6 +103,10 @@ type UserStore interface {
 	// Excludes the calling user. Max 20 results.
 	SearchActive(ctx context.Context, excludeUserID, query string) ([]UserSearchResult, error)
 
+	// ResolveByIDs returns lightweight identity records for the given user IDs.
+	// Missing IDs are silently omitted. Max 100 IDs.
+	ResolveByIDs(ctx context.Context, ids []string) ([]UserSearchResult, error)
+
 	// ── CS2 additions ──
 
 	// CountAll returns the total number of users.
@@ -132,6 +136,7 @@ type UserSearchResult struct {
 	Username    string `json:"username"`
 	DisplayName string `json:"display_name"`
 	Handle      string `json:"handle"`
+	AvatarURL   string `json:"avatar_url,omitempty"`
 }
 
 // =========================================