fix: message handle (#14178)

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

* **Bug Fixes**
* Robustly sanitize session titles, messages, attachments, and embedded
data to remove invalid/null characters and prevent corrupt persistence.
* Improve chat title generation to skip or recover from invalid input
and log contextual errors without crashing.
* Add more detailed storage and workspace logs and reduce repetitive
checks to aid troubleshooting and stability.

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settings.</sub>
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/backend/server/src/plugins/copilot/embedding/job.ts

@@ -533,7 +533,15 @@ export class CopilotEmbeddingJob {
       workspaceId
     );
     if (!snapshot) {
-      this.logger.warn(`workspace snapshot ${workspaceId} not found`);
+      // maybe local workspace or empty workspace
+      this.logger.verbose(`workspace root snapshot ${workspaceId} not found`);
+      // mark last check time to avoid repeated checking
+      await this.models.workspace.update(
+        workspaceId,
+        { lastCheckEmbeddings: new Date() },
+        false
+      );
+
       return;
     } else if (
       // always check if never cleared