Refactored case statements and conditional checks to use more idiomatic and consistent Bash syntax. Replaced German comments with English, improved readability by splitting long lines, and standardized variable assignments. Enhanced maintainability by using case/esac and if/then constructs, and replaced double-bracketed conditionals with POSIX-compliant single brackets where appropriate.
Added new preset and menu options for App Defaults, Diagnostics, and Storage Settings. Refactored the menu to be dynamically built and improved handling for each choice, including better diagnostics toggling and support for app-specific defaults. This enhances flexibility and user experience in the installation script.
Reworks the app defaults save/update logic in misc/build.func to support updating existing defaults with a diff and interactive menu, and adds robust var_* parsing and whitelisting. Removes legacy error and curl handler functions from misc/core.func, streamlining error handling and reducing code duplication.
Changed default OS version from Debian 12 to 13 and updated the GlobaLeaks APT repository to use 'trixie' instead of 'bookworm'. Also switched apt-get commands to apt for consistency and modern usage.
