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/chroot.py

@@ -0,0 +1,23 @@
+"""Mount an image and open an interactive shell inside it."""
+
+from lim import device as device_module
+from lim import runner, ui
+from lim.image.session import ImageSession
+
+
+def run_chroot() -> None:
+    ui.info("Starting chroot...")
+    device = device_module.select_device()
+    session = ImageSession(device)
+    try:
+        session.make_working_folder()
+        session.make_mount_folders()
+        session.decrypt_root()
+        session.mount_partitions()
+        session.mount_chroot_binds()
+        session.copy_qemu()
+        session.copy_resolv_conf()
+        ui.info("Bash shell starts...")
+        runner.run(["chroot", str(session.root_mount_path), "/bin/bash"], sudo=True)
+    finally:
+        session.destructor()