fix: replace raw echo with output helpers in general/wallpaper

[github-actions]

Summary

• Replaced the non-standard die() implementation with the canonical die/success/info output helpers
• Replaced all bare echo calls with the appropriate helper: info for progress announcements, success for completion messages
• Script behaviour is preserved; only output formatting has changed

Closes #640

Test plan

• Script passes shellcheck (verified via pre-commit hook)
• All bare echo calls removed and replaced with die/info/success
• Script behaviour unchanged

[dnyw4l3n13]

All CI checks are passing. The general/wallpaper script now uses the canonical die/success/info output helpers in place of all bare echo calls. Implementation matches the reference pattern from shell-scripts.examples.md exactly. PR is ready for review.

[credfeto]

Super-linter summary

Language	Validation result
BASH	Pass ✅

All files and directories linted successfully

For more information, see the GitHub Actions workflow run

Powered by Super-linter

[dnyw4l3n13]

All CI checks are passing and no review comments require action. PR is complete and ready for merge.

[credfeto]

Super-linter summary

Language	Validation result

All files and directories linted successfully

For more information, see the GitHub Actions workflow run

Powered by Super-linter