Initial backup of LTP-305G matrix clock setup on matrixpi

Captures everything needed to redeploy the two-display clock (hour on I2C
0x61, minute on I2C 0x63) on a fresh Pi:

- Both systemd units (matrix0x61.service, matrix0x63.service)
- Deployed Pimoroni script tree, including the local %I (12-hour) clock
  customization
- Vendored upstream sources (ltp305-python, breakout-garden) so restore is
  fully offline-capable
- Boot config snippet enabling I2C
- install.sh that wires it all back up idempotently
- Inventory doc cross-referencing every live-system path

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

vendor/ltp305-python/library/tests/conftest.py

@@ -0,0 +1,22 @@
+import sys
+import mock
+import pytest
+
+
+@pytest.fixture(scope='function', autouse=True)
+def cleanup():
+    """Force module reimport between tests."""
+    yield None
+    try:
+        del sys.modules['ltp305']
+    except KeyError:
+        pass
+
+
+@pytest.fixture(scope='function', autouse=False)
+def smbus():
+    """Mock smbus module."""
+    smbus = mock.MagicMock()
+    sys.modules['smbus'] = smbus
+    yield smbus
+    del sys.modules['smbus']