## Description
Adds a guarded retry action for Intercom imports that have not recorded
progress for 15 minutes. The API reports stalled state, rotates the
import run identifier under an account lock, preserves existing progress
and logs, and queues a fresh worker only when no other Intercom import
is active for the account. The import details page shows Retry
immediately before Abandon only while the server reports the import as
stalled.
This is Phase 1, Task 1 of the [Intercom import optimization plan
(CW-7615)](https://linear.app/chatwoot/issue/CW-7615/optimize-intercom-import-reliability-and-bulk-message-ingestion).
This replaces #15049 with the updated 15-minute threshold and is based
directly on the latest `develop`.
## Closes
-
[CW-7519](https://linear.app/chatwoot/issue/CW-7519/explore-intercom-import)
## Type of change
- [x] New feature (non-breaking change which adds functionality)
## How to test
1. Open a processing Intercom import updated within the last 15 minutes
and confirm Retry is hidden.
2. Set its updated timestamp to more than 15 minutes ago and reload the
details page.
3. Confirm Retry appears immediately before Abandon.
4. Retry the import and confirm it returns to Pending while existing
progress, logs, and the original start time remain intact.
5. Confirm a second retry is rejected and another active Intercom import
prevents queueing.
## Checklist
- [x] My code follows the style guidelines of this project
- [x] I have performed a self-review of my code
- [x] I have added tests that prove the change is effective
- [x] New and existing focused tests pass locally with my changes
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