feat(auth): add active sessions management

- store refresh session metadata in redis (ip/user-agent/created_at)

- add auth APIs: list sessions, revoke one, revoke all

- add web privacy UI for active sessions

web/src/chat/types.ts

@@ -88,6 +88,13 @@ export interface TokenPair {
   token_type: string;
 }
 
+export interface AuthSession {
+  jti: string;
+  created_at: string;
+  ip_address?: string | null;
+  user_agent?: string | null;
+}
+
 export interface UserSearchItem {
   id: number;
   name: string;