fix: resolve startup crashes and layout instabilities in 2.13.1 release

[yassine20011]

Description

This pull request releases version 2.13.1 of KVitals, focusing on fixing several startup crashes, color validation issues, and UI glitches. The update introduces multiple stability improvements and bug fixes, particularly around boot-time sensor initialization and QML property bindings.

Bug fixes and stability improvements:

• Fixed a SEGV_ACCERR crash at startup by improving initialization checks and guarding sensor readiness for Network and Disk metrics.
• Addressed a Kirigami icon crash at startup by deferring isMask and color property assignments until after the theme is fully initialized.
• Added hex-regex validation for color configuration properties to prevent invalid colors from propagating to Kirigami.
• Gated Disk and Network sensor model initialization behind startup timers to prevent crashes due to premature D-Bus subscriptions.
• Deferred USB hotplug detection initialization to avoid startup-time crashes related to Solid/UDisks2 plugins.

UI and configuration fixes:

• Resolved a font family binding loop and ensured custom font families are always applied, even at system-default sizes.
• Improved panel layout stability by refining width cache logic in CompactView.
• Merged duplicate signal connections in the disk sensor model to reduce overhead.

Other changes:

• Updated the version number to 2.13.1 in metadata.json.

[greptile-apps]

Greptile Summary

Releases KVitals 2.13.1.

• Documents the startup stability, color validation, sensor initialization, font binding, and panel layout fixes included in the release.
• Updates the Plasma applet metadata version from 2.13.0 to 2.13.1.

Confidence Score: 5/5

The release documentation and metadata update appear safe to merge.

The version bump matches the new changelog entry, and the implementation changes described by that entry are already included in the release tree.

Important Files Changed

Filename	Overview
CHANGELOG.md	Adds release notes for version 2.13.1 describing fixes already present in the release tree; no actionable issue identified.
metadata.json	Bumps the applet package version from 2.13.0 to 2.13.1 consistently with the changelog; no actionable issue identified.

_{Reviews (1): Last reviewed commit: "fix: resolve startup crashes and layout ..." | Re-trigger Greptile}