## Description
Reduces sustained load during large Intercom imports by limiting
conversation list pages to 10 while retaining 50-contact pages. Cursor
and provider total-count behavior remain unchanged.
The one-minute progress heartbeat now lives in parent PR #15050 because
stalled-import detection must be safe when that PR is deployed
independently. This child PR therefore contains only the smaller-page
delta.
This is Phase 1, Task 2 of the [Intercom import optimization plan
(CW-7615)](https://linear.app/chatwoot/issue/CW-7615/optimize-intercom-import-reliability-and-bulk-message-ingestion).
This PR is stacked on #15050 and should be reviewed as the two-file
delta from `codex/cw-7519-intercom-stalled-retry-15m`.
## Closes
-
[CW-7615](https://linear.app/chatwoot/issue/CW-7615/optimize-intercom-import-reliability-and-bulk-message-ingestion)
## Type of change
- [x] Bug fix (non-breaking change which fixes an issue)
## How to test
1. Start an Intercom import containing contacts and conversations across
multiple source pages.
2. Confirm contact list requests retain a page size of 50.
3. Confirm conversation list requests use a page size of 10.
4. Confirm page cursors and displayed provider totals continue advancing
normally.
5. Confirm the parent PR heartbeat keeps long conversations fresh while
these shorter pages are processed.
## 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
