fix(server): log inner errors of WorkspaceMigrationRunnerException in workspace iterator (#19823)

## Summary

When a workspace migration action fails during workspace iteration (e.g.
during upgrade commands), only the wrapper message was logged:

```
[WorkspaceIteratorService] Error in workspace 7914ba64-...: Migration action 'create' for 'pageLayoutWidget' failed
```

The underlying error (transpilation/metadata/workspace schema) and its
stack were swallowed, making production debugging painful.

This PR adds a follow-up log entry for each inner error attached to a
`WorkspaceMigrationRunnerException`, including its message and stack
trace. The runner exception itself is untouched — it already exposes
structured `errors` (`actionTranspilation`, `metadata`,
`workspaceSchema`).

After this change, logs look like:

```
[WorkspaceIteratorService] Error in workspace 7914ba64-...: Migration action 'create' for 'pageLayoutWidget' failed
[WorkspaceIteratorService] Caused by actionTranspilation in workspace 7914ba64-...: <real reason>
    at ...
```

## Test plan

- [ ] Trigger a failing workspace migration (e.g. backfill record page
layouts) on a workspace and confirm the underlying cause + stack now
appear in logs.

Made with [Cursor](https://cursor.com)

packages/twenty-server/src/database/commands/command-runners/workspace-iterator.service.ts

@@ -4,12 +4,14 @@ import { InjectRepository } from '@nestjs/typeorm';
 import chalk from 'chalk';
 import { isNonEmptyString } from '@sniptt/guards';
 import { WorkspaceActivationStatus } from 'twenty-shared/workspace';
+import { isDefined } from 'twenty-shared/utils';
 import { In, MoreThanOrEqual, Repository } from 'typeorm';
 
 import { WorkspaceEntity } from 'src/engine/core-modules/workspace/workspace.entity';
 import { GlobalWorkspaceDataSource } from 'src/engine/twenty-orm/global-workspace-datasource/global-workspace-datasource';
 import { GlobalWorkspaceOrmManager } from 'src/engine/twenty-orm/global-workspace-datasource/global-workspace-orm.manager';
 import { buildSystemAuthContext } from 'src/engine/twenty-orm/utils/build-system-auth-context.util';
+import { WorkspaceMigrationRunnerException } from 'src/engine/workspace-manager/workspace-migration/workspace-migration-runner/exceptions/workspace-migration-runner.exception';
 
 export type WorkspaceIteratorArgs = {
   workspaceIds?: string[];
@@ -104,12 +106,29 @@ export class WorkspaceIteratorService {
       }
     }
 
-    report.fail.forEach(({ error, workspaceId }) =>
+    report.fail.forEach(({ error, workspaceId }) => {
       this.logger.error(
         `Error in workspace ${workspaceId}: ${error.message}`,
         error.stack,
-      ),
-    );
+      );
+
+      if (error instanceof WorkspaceMigrationRunnerException && error.errors) {
+        for (const [label, innerError] of Object.entries(error.errors)) {
+          if (!isDefined(innerError)) continue;
+
+          if (innerError instanceof Error) {
+            this.logger.error(
+              `Caused by ${label} in workspace ${workspaceId}: ${innerError.message}`,
+              innerError.stack,
+            );
+          } else {
+            this.logger.error(
+              `Caused by ${label} in workspace ${workspaceId}: ${String(innerError)}`,
+            );
+          }
+        }
+      }
+    });
 
     return report;
   }