Remove CSS/JS merge functionality

[sreichel]

Description (*)

Fixed Issues (if relevant)

• closes [FEAT] Warning in the backend if css/js files are missing #4740

[Copilot]

Pull Request Overview

This PR removes the deprecated CSS/JS file merging functionality from OpenMage. The merge feature combined multiple CSS and JavaScript files into single files to reduce HTTP requests, but modern HTTP/2+ and asset management practices make this approach obsolete.

Key changes:

• Removed merge configuration options from system settings
• Deleted merge-related methods from core models and helpers
• Cleaned up admin UI elements related to cache flushing
• Updated localization strings to remove merge-related messages

Reviewed Changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
app/locale/en_US/Mage_Core.csv	Removed translation keys for CSS/JS settings and merge options
app/locale/en_US/Mage_Adminhtml.csv	Removed translation keys for JS/CSS cache clearing functionality
app/design/adminhtml/default/default/template/system/cache/additional.phtml	Removed "Flush JavaScript/CSS Cache" button from cache management page
app/code/core/Mage/Page/Block/Html/Head.php	Removed merge callback logic and simplified file preparation methods
app/code/core/Mage/Core/etc/system.xml	Removed JavaScript and CSS settings sections from system configuration
app/code/core/Mage/Core/etc/config.xml	Removed default JS merge configuration
app/code/core/Mage/Core/Model/Design/Package.php	Removed merge URL generation methods and CSS processing callbacks, updated docblocks
app/code/core/Mage/Core/Helper/Data.php	Removed mergeFiles method, refactored variable names for clarity
app/code/core/Mage/Adminhtml/controllers/System/CacheController.php	Removed JS/CSS cache clearing logic from save action
app/code/core/Mage/Adminhtml/controllers/CacheController.php	Removed cleanMediaAction method
app/code/core/Mage/Adminhtml/Model/System/Config/Backend/Secure.php	Deleted entire file (cleanup hook no longer needed)
app/code/core/Mage/Adminhtml/Model/System/Config/Backend/Baseurl.php	Removed _afterSave method that cleaned merged files
app/code/core/Mage/Adminhtml/Block/Cache/Additional.php	Removed getCleanMediaUrl method
.phpstan.dist.baseline.neon	Removed baseline entry for nullable property warning

Comments suppressed due to low confidence (1)

app/code/core/Mage/Page/Block/Html/Head.php:123

• The third parameter passed to _prepareStaticAndSkinElements is now always null since merge functionality has been removed. Consider removing the $mergeCallback parameter entirely from the method signature to simplify the API and prevent confusion.

    public function addItem($type, $name, $params = null, $if = null, $cond = null, $referenceName = '*', $before = false)

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud