Display page count changes in tt update output

[F0rgenet]

Description

When running tt update, display information about page count changes for tests, similar to how tt run already reports them. Currently, tt run shows page count deviations (e.g., "Expected 1 page, got 2 pages"), but tt update silently updates snapshots without indicating if pagination has changed.

For example, when running:

forgenet@fedora ~/P/t/modern-g7-32 (main)> tt update
  Starting 36 tests, 5 filtered (run ID: ae2367b7-e9b5-4619-9523-b94b9669a707)
    update [ 1s  22ms] features/definitions/abstract/count-false

The output should indicate page count changes, such as:

    update [ 1s  22ms] features/definitions/abstract/count-false (pages: 1 → 3)

This would maintain consistency with tt run output and help developers immediately notice when their changes cause unexpected pagination differences.

Alternative Solutions

Currently, the only way to detect page count changes after running tt update is to manually check the snapshot files or run tt run separately, which is time-consuming.

Additional Context

The tt run command already displays page count changes (e.g., "Expected 15 pages, got 16 pages"), making it inconsistent that tt update doesn't show this information. Displaying page count changes during update would improve developer workflow by catching pagination issues immediately.

[tingerrr]

I think we can go one step further and also show which pages were actually updated too, I suppose.