refactor!: port shell scripts to Python package

Bash scripts were untestable and duplicated device/LUKS/mount logic;
the lim/ package centralizes it behind one subprocess wrapper and a
YAML image catalog (single point of truth).

BREAKING CHANGE: scripts/*.sh removed. Use `lim --type <cmd>`; new
types mount/umount/single-boot/raid1-boot/lock/unlock/import/export
replace direct script calls. --extra is deprecated and ignored.

- distributions.yml + lim/catalog.py hold the image catalog (PyYAML)
- pytest suite: 102 tests with mocked subprocess (tests/unit) and a
  250-line max file-length guard (tests/lint)
- ruff strict (select ALL), GitHub Actions CI, Dependabot; Travis gone
- Makefile: install (symlink ~/.local/bin/lim) and test targets
- fixes over bash: SUDO_USER-aware chown, mmcblk/nvme partition paths,
  sha512 checksum support, whole-pipeline failure detection, blkid
  UUID fallback for pre-mounted images, conditional fstab seeding for
  PARTUUID/LABEL images, clean errors for missing binaries

lim/image/backup.py

@@ -0,0 +1,32 @@
+"""Create an image backup from a memory device into a file."""
+
+from pathlib import Path
+
+from lim import device as device_module
+from lim import runner, ui
+
+
+def run_backup() -> None:
+    ui.info("Backupscript for memory devices started...")
+    print()
+    device = device_module.select_device()
+
+    working_dir = Path.cwd()
+    path = ""
+    while not path:
+        path = ui.ask(f"Please type in backup image path+name relative to {working_dir}:")
+    output_file = f"{path}.img" if path.startswith("/") else f"{working_dir}/{path}.img"
+
+    ui.info(f"Input file: {device.path}")
+    ui.info(f"Output file: {output_file}")
+    ui.ask('Please confirm by pushing "Enter". To cancel use "Ctrl + C"')
+
+    ui.info("Imagetransfer starts. This can take a while...")
+    runner.run(
+        ["dd", f"if={device.path}", f"of={output_file}", "bs=1M", "status=progress"],
+        sudo=True,
+        error_msg='"dd" failed.',
+    )
+    runner.sync_disks()
+
+    ui.success("Imagetransfer successfull.")