ENH: refactor Restore Dialog

[tiffany-slac]

Description

This PR refactors the Restore dialog in the Snapshot details page. Instead of displaying a full PV table inside the dialog, the dialog now shows a simple confirmation message. Users who want to review the PVs they’ve selected can use the newly added filter.

• Added a "Show selected" checkbox above the PV table to filter displayed PVs
• Removed the PV table from the Restore dialog and made it more compact
• Adjusted dialog width and padding

Motivation

Closes #13

Previously, the dialog contained a PV table which was redundant since users can filter and select PVs on the main page. This change:

• Removed PVTable from the dialog content
• Improved responsiveness when cancelling the dialog after removing the PVTable (Closes Canceling the snapshot restore dialog takes a few seconds, which seems long #14)
• Added a concise message indicating how many PVs will be restored
• Adjusted dialog width and padding to improve alignment

Screenshots

New 'Show selected ( )' Filter

Restore Dialog

Pre-merge checklist

• Code works interactively
• Code follows the style guide
• Code contains descriptive docstrings
• New/changed functions and methods are covered in the test suite where possible
• Test suite passes locally
• Test suite passes on GitHub Actions