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

tests/unit/test_raspberry.py

@@ -0,0 +1,72 @@
+import pytest
+
+from lim.device import Device
+from lim.image import raspberry
+from lim.image.session import ImageSession
+
+
+@pytest.fixture
+def session(tmp_path):
+    session = ImageSession(Device("mmcblk0"))
+    session.root_mount_path = tmp_path
+    session.boot_partition_uuid = "BOOT-UUID"
+    return session
+
+
+class TestSeedBootUuid:
+    def test_replaces_mmcblk_reference(self, tmp_path, session):
+        fstab = tmp_path / "etc/fstab"
+        fstab.parent.mkdir()
+        fstab.write_text("/dev/mmcblk0p1  /boot  vfat  defaults  0  0\n")
+        raspberry._seed_boot_uuid(session)
+        assert fstab.read_text() == "UUID=BOOT-UUID  /boot  vfat  defaults  0  0\n"
+
+    def test_skips_partuuid_based_images(self, tmp_path, session):
+        fstab = tmp_path / "etc/fstab"
+        fstab.parent.mkdir()
+        content = "PARTUUID=6c586e13-01  /boot  vfat  defaults  0  0\n"
+        fstab.write_text(content)
+        raspberry._seed_boot_uuid(session)  # must not raise
+        assert fstab.read_text() == content
+
+
+class TestEnsureImageMounted:
+    def test_reads_uuids_when_boot_already_mounted(self, fake_runner):
+        session = ImageSession(Device("sda"))
+        fake_runner.outputs["mount"] = "/dev/sda1 on /tmp/x/boot type vfat (rw)"
+        # Distinct per-partition values so a boot/root swap cannot pass.
+        fake_runner.outputs["/dev/sda1 -s UUID"] = "boot-uuid"
+        fake_runner.outputs["/dev/sda2 -s UUID"] = "root-uuid"
+        fake_runner.outputs["-s TYPE"] = "crypto_LUKS"
+
+        raspberry._ensure_image_mounted(session)
+
+        assert session.boot_partition_uuid == "boot-uuid"
+        assert session.root_partition_uuid == "root-uuid"
+        assert session.root_mapper_name == "linux-image-manager-root-uuid"
+        assert session.root_mapper_path == "/dev/mapper/linux-image-manager-root-uuid"
+
+    def test_plain_root_keeps_partition_as_mapper(self, fake_runner):
+        session = ImageSession(Device("sda"))
+        fake_runner.outputs["mount"] = "/dev/sda1 on /tmp/x/boot type vfat (rw)"
+        fake_runner.outputs["-s UUID"] = "uuid-7"
+        fake_runner.outputs["-s TYPE"] = "ext4"
+
+        raspberry._ensure_image_mounted(session)
+
+        assert session.root_mapper_name is None
+        assert session.root_mapper_path == "/dev/sda2"
+
+    def test_mounts_when_nothing_is_mounted(self, fake_runner, tmp_path):
+        session = ImageSession(Device("sda"))
+        session.boot_mount_path = tmp_path / "boot"
+        session.root_mount_path = tmp_path / "root"
+        fake_runner.outputs["-s TYPE"] = "ext4"
+        fake_runner.outputs["/dev/sda1 -s UUID"] = "boot-uuid"
+        fake_runner.outputs["/dev/sda2 -s UUID"] = "root-uuid"
+
+        raspberry._ensure_image_mounted(session)
+
+        assert len(fake_runner.find("mount", "-v")) == 2
+        assert session.boot_partition_uuid == "boot-uuid"
+        assert session.root_partition_uuid == "root-uuid"