fix: Rename merge operation title to "Merge (combine)" in keyboard shortcuts

[Ayushdas1904]

fixes #11557

Description

Updates the keyboard shortcuts list entry for the merge operation from "Merge" to "Merge (combine)". This improves discoverability while keeping "Merge" as the primary, more intuitive name.

Changes

• Updated merge operation title in data/core.yaml from "Merge" to "Merge (combine)"
• Users can now search for either "merge" or "combine" when looking for this operation
• Maintains consistency with existing help text that refers to "combining" features

Testing

• Keyboard shortcuts list displays "C Merge (combine)"
• Help text for merge operation correctly references the updated title
• npm test passes
• npm start shows correct UI rendering

Checklist

• Code change is complete
• Tests pass
• CHANGELOG.md updated (if applicable)

[Ayushdas1904]

Hey @tyrasd , take a look at this PR