feat(server): add generate title cron resolver (#13189)

fix AI-350

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **New Features**
* Added a new option to manually trigger the generation of missing
session titles via a GraphQL query.

* **Improvements**
* The process for generating missing session titles now considers all
eligible sessions, without limiting the number processed at a time.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/backend/server/src/models/copilot-session.ts

@@ -613,7 +613,7 @@ export class CopilotSessionModel extends BaseModel {
   }
 
   @Transactional()
-  async toBeGenerateTitle(take: number) {
+  async toBeGenerateTitle() {
     const sessions = await this.db.aiSession
       .findMany({
         where: {
@@ -628,7 +628,6 @@ export class CopilotSessionModel extends BaseModel {
           // count assistant messages
           _count: { select: { messages: { where: { role: 'assistant' } } } },
         },
-        take,
         orderBy: { updatedAt: 'desc' },
       })
       .then(s => s.filter(s => s._count.messages > 0));