Remove unused css file to keep codebase clean

[AbiT-246]

PR Summary:

Why are these changes introduced?

Fixes #3781

Removes unused CSS file component-progress-bar.css that was not being imported or referenced anywhere in the codebase. The progress bar component functionality remains intact as it uses styles defined in base.css (lines 3564-3597) rather than a separate component CSS file.

What approach did you take?

Removed the unused CSS file after ensuring it is not being imported and used anywhere. Verified that:

• No liquid files import component-progress-bar.css
• No references to the file exist in the codebase
• Progress bar styles are already defined in base.css and continue to work with the existing progress-bar.liquid snippet

Other considerations

This is a cleanup change with no functional impact. The progress bar component continues to work as expected since its styles are defined in base.css.

Decision log

#	Decision	Alternatives	Rationale	Downsides
1	Remove unused CSS file	Keep the file for potential future use	Reduces codebase size and maintenance burden. The file was not being used and progress bar styles already exist in base.css	None - file was completely unused

Visual impact on existing themes

No visual impact. This change only removes an unused CSS file. All progress bar styling remains in base.css and continues to function identically.

Testing steps/scenarios

• Verified no references to component-progress-bar.css exist in the codebase
• Verified progress bar component still renders correctly (test with progress-bar.liquid snippet)
• Tested theme compilation/build process completes successfully
• Verified no console errors or missing asset warnings in browser
• Tested on mobile browsers
• Tested on multiple desktop browsers (Chrome, Firefox, Safari, Edge)

Checklist

• Added PR summary for release notes

• Requested review from UX (Only for changes that are affecting the experience or perceivable visual details)

• Created a ticket for the help.shopify.com documentation team about updates to theme settings. (Internal-only task)

• Followed theme code principles

• Linted with Theme Check

• Tested on mobile

• Tested on multiple browsers

• Tested for accessibility