[REQUEST] Improve system stability & automatic cleanup for rolling release

### Problem / Motivation

CachyOS is a powerful rolling-release distro with excellent performance, but frequent system updates sometimes break existing functionality. For example:

1. Package stability: After recent updates, core KDE apps like Spectacle developed bugs (save dialog hijacked by HEIF/AVIF plugins) that do not exist on other distros with the same Plasma version (e.g., openSUSE Tumbleweed). This suggests CachyOS-specific packaging or build configuration issues.

2. System bloat: Over time, the system accumulates large amounts of build cache, orphaned packages, and leftover files — especially for users who install from AUR. There is no built-in automatic cleanup mechanism.

CachyOS markets itself as a performance-focused, user-friendly Arch alternative. But new users (and even experienced ones) are often surprised when a routine pacman -Syu breaks screenshot tools, image viewers, or other core desktop functionality.

##Proposed Solution

1. Stability-focused update channel (optional)
- A "stable" or "delayed" repo option that holds updates for 24-48 hours after Arch upstream, allowing critical bugs to be caught before reaching users.
- Or a pre-update warning system if a package update is known to break common desktop workflows.

2. Built-in automatic system cleanup
- A weekly/monthly systemd timer that safely clears:
- Orphaned packages (pacman -Rns $(pacman -Qtdq))
- Old package cache (pacman -Sc)
- User app caches (thumbnails, browser cache, etc.)
- Old build caches from ~/.cache/yay/
- A simple GUI toggle in System Settings: "Enable automatic system cleanup"

3. Package integrity verification after updates
- After pacman -Syu, optionally run pacman -Qk to verify no files were corrupted/missed during update.
- Alert user if any package has missing files.

4. Better AUR build isolation
- AUR builds currently dump everything into ~/.cache/yay/ and can leave behind multi-GB folders if interrupted (e.g., webkit2gtk build). Consider:
- Automatic cleanup of failed/incomplete AUR builds
- Or building in /tmp by default with automatic wipe

### Alternatives Considered
Currently using manual workarounds:
- Custom cleanup scripts run manually
- Avoiding AUR builds when possible
- Using alternative apps (Flameshot instead of Spectacle) when CachyOS packages break
- Removing libheif and disabling kimageformats plugins manually

These workarounds are not sustainable for average users and do not address the root cause.

### Additional Context

This request is based on real-world usage experience on CachyOS with KDE Plasma 6.7.4. The system is fast and well-optimized, but the maintenance overhead is higher than it should be for a distro that targets user-friendliness.
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The issue names no repository files, tests, or implementation entry points; start by checking whether this placeholder repository contains code for any of the requested features. The proposed cleanup, update-channel, integrity-check, and AUR-isolation changes need to be narrowed to one deliverable before completion can be defined.

Written by the indexing model from the issue text.