feat: session source in session_meta and an Automated sidebar folder (#40)

Co-authored-by: Alice <alice@prismshadow.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

packages/server/src/api/types.ts

@@ -454,7 +454,7 @@ export interface SessionInfo {
   approvalMode: ApprovalMode;
   /** Short title auto-generated by the model after the first turn; unset until generated (frontend shows "New Chat"). */
   title?: string;
-  /** Session source (for list badges); unset for user-created sessions. */
+  /** Session source (for list badges/folders), derived from core session_meta — the single source of truth (not stored in the DB); unset for user-created sessions. */
   source?: SessionSource;
   createdAt: string;
   status: SessionStatus;