Update all copyright notices in shell scripts from 2025 to 2026.
## Changes
- **Igor Pecovnik**: 2013-2025 → 2013-2026 (129 files)
- **Ricardo Pardini**: 2023-2025 → 2023-2026, 2020-2025 → 2020-2026 (5 files)
## Additional Improvements
Also updated the backtitle in `lib/functions/configuration/interactive.sh`:
- Changed title from "Armbian building script" to "Armbian Linux build framework"
- Removed docs link for cleaner display
- Uses dynamic year calculation with separate declaration (fixes shellcheck SC2155)
- Fixes: 71296430fa -- which only set `SKIP_ARMBIAN_REPO=yes` when `rootfs` cli shortcut used
- GHA artifact pipelines are generic across all artifacts, and don't use the cli shortcuts
- instead, they use the `artifact` shortcut, with the `WHAT=rootfs` parameter
- so in GHA pipelines `SKIP_ARMBIAN_REPO=yes` was not taking effect
- rootfs artifact itself now enforces `SKIP_ARMBIAN_REPO` to be `yes` and makes it readonly
- also add `SKIP_ARMBIAN_REPO` to the general change-tracking for more clarity about configs and hooks etc
- add change tracking calls before/after generic artifact config adapter for even more clarity
- `NETWORKING_STACK` can be set to `none` (in config phase, pre-extensions) to not-add any networking extensions
- keep defaulting to systemd-networkd if BUILD_MINIMAL and NetworkManager otherwise
- fix typo in extension name
- add `NETWORKING_STACK` to change-tracking
