Solves problems in "feat(pdf): add optional tile borders to PDF export (#1954)" PR

[magush27]

This PR fixes several issues found in #1960 that prevented the tile borders feature from working correctly:

Things fixed

1. CHANGELOG.md - Removed the changelog entry as asked by one of the mantainers.
2. Export.component.js - Fixed incorrect method name reference
3. Export.helpers.js - Removed broken code block, fixed parameter passing throughout the call chain and implemented actual border rendering logic
4. Export.messages.js - Added proper internationalization
5. Export.component.js - Fixed UI layout overlap

Testing
To test:

1. Navigate to Settings > Export
2. Select a board
3. Toggle "Show borders around tiles in PDF" checkbox
4. Choose PDF export
5. Export with checkbox unchecked, tiles should have subtle internal borders (default)
6. Export with checkbox checked, tiles should have visible black borders around them

Fixes #1960