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/examples/clock.py

@@ -0,0 +1,50 @@
+import sys
+import time
+from ltp305 import LTP305
+
+
+print("""clock.py - clock segment example.
+
+Usage: python3 clock.py <hour/minute/second> <i2c-address>
+
+This simple clock example will display the hour, minute or second on a single matrix display breakout.
+
+Press Ctrl+C to exit.
+
+""")
+
+fmt = "%M"
+address = 0x61
+available = {
+    "hour": "%H",
+    "minute": "%M",
+    "second": "%S"
+}
+
+if len(sys.argv) > 1:
+    try:
+        fmt = available[sys.argv[1]]
+    except KeyError:
+        raise ValueError("{} is not supported!".format(sys.argv[1]))
+
+if len(sys.argv) > 2:
+    address = int(sys.argv[2], 16)
+    if address not in [0x61, 0x62, 0x63]:
+        raise ValueError("Invalid i2c address: 0x{:02x}. Run `i2c-detect -y 1` to discover breakouts.".format(address))
+
+
+try:
+    display = LTP305(address=address)
+    display.clear()
+    display.show()
+except OSError:
+    raise OSError("Unable to find LTP305 on i2c address: 0x{:02x}. Run `i2c-detect -y 1` to discover breakouts".format(address))
+
+
+while True:
+    minute = time.strftime(fmt)
+    left, right = minute
+    display.set_character(0, left)
+    display.set_character(5, right)
+    display.show()
+    time.sleep(1.0 / 60)