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/bargraph.py

@@ -0,0 +1,43 @@
+import time
+import math
+import random
+from ltp305 import LTP305
+
+
+print("""bargraph.py - A basic graph example
+
+Displays an animated rising/falling bar on the left matrix,
+and a scrolling bar graph on the right.
+
+Press Ctrl+C to exit!
+
+""")
+
+display = LTP305()
+width, height = display.get_shape()
+
+values = [0, 0, 0, 0, 0]
+
+
+while True:
+    # Add a new random value to our list and prune the list to visible values
+    values.insert(0, random.randint(0, height))
+    values = values[:width]
+
+    # Animate a value from 0 to height + 1
+    value = (math.sin(time.time() * math.pi) + 1) / 2.0
+    value *= height + 1
+    value = math.floor(value)
+
+    for y in range(height):
+        y = height - 1 - y
+
+        for x in range(width // 2):
+            # Left
+            display.set_pixel(x, y, value <= y)
+
+            # Right
+            display.set_pixel(x + (width // 2), y, values[x] <= y)
+
+    time.sleep(1.0 / height)
+    display.show()