debian-update v0.11.5 (RC3) - Refinements & Hardening

Release Candidate 3 (v0.11.5) brings major stability hardening, codebase cleanup, and strict Debian Policy compliance as the final candidate milestone towards the v1.0 LTS release.

100% Passive Status Detection: Reads UEFI state directly from Linux sysfs (/sys/firmware/efi/efivars/), avoiding external binaries or intrusive privileged checks during background polling.
Intelligent Signature Verification: Checks existing module signatures (modinfo -F signer) and kernel signatures (sbverify). If all modules and kernels are already signed (e.g. by DKMS during APT operations), the signing process completes silently in milliseconds without redundant re-signing.
Strict Standard Key Scoping: Key discovery is strictly restricted to official system paths (/var/lib/dkms/, /var/lib/shim-signed/mok/), preventing accidental access to foreign disks or external keys.
Zero Overhead on Non-SB Systems: The signing subsystem remains completely silent and inactive on systems without Secure Boot enabled.

Eliminated Experimental Held-Back Interventions: Removed custom package solver logic to prevent unintended package removals during Debian Sid/Testing library transitions.
1:1 Status Sync: Switched backend background checking from dist-upgrade to upgrade simulation, ensuring the system tray applet accurately reflects only packages that standard apt upgrade will install without false positives.
Safe, Interactive Execution: Respects standard Debian package management prompts and policy safeguards.

Complete Removal of deb-get and AppImages: Removed all legacy binaries, background subshells, dependencies, and menu entries to keep the application lean and native.
Debian Policy Compliance: Package metadata in DEBIAN/control has been strictly restructured according to the Debian Policy Manual:
- Depends: python3:any, python3-pyqt5, python3-pyqt5.qtsvg
- Recommends: needrestart, flatpak, apt-listbugs, sbsigntool
- Suggests: snapd
Modern Terminal Support: Expanded terminal emulator auto-detection across desktop environments (ptyxis, kgx, gnome-console, kitty, alacritty, foot, cosmic-term, konsole, xfce4-terminal, etc.).

Periodic Ko-fi Support Option: Added an optional Ko-fi menu action in the system tray applet that is visible for the first 24 hours after install, and then appears for 24 hours every 30 days.
Full i18n Synchronization: All 20 supported languages (Nordic, European, Asian) are 100% synchronized with 65 identical translation keys.
Documentation: Overhauled README.md with sober, clear, and professional technical documentation.