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/breakout-garden/examples/colour-control/colour-control.py

@@ -0,0 +1,80 @@
+#!/usr/bin/env python3
+
+import time
+import colorsys
+import atexit
+
+from trackball import TrackBall
+from rgbmatrix5x5 import RGBMatrix5x5
+
+print("""This Pimoroni Breakout Garden example requires an
+Trackball Breakout and a 5x5 RGB Matrix Breakout.
+
+Use the trackball and switch to control the hue and
+brightness of the trackball's RGBW LEDs.
+
+Scroll up to increase brightness and left/right
+to change hue. Click to turn on/off.
+
+Press Ctrl+C to exit.
+""")
+
+# Set up the trackball
+trackball = TrackBall(interrupt_pin=4)
+
+@atexit.register
+def clear_trackball():
+    trackball.set_rgbw(0, 0, 0, 0)
+
+# Set up the 5x5 RGB matrix
+rgbmatrix5x5 = RGBMatrix5x5()
+rgbmatrix5x5.set_clear_on_exit()
+rgbmatrix5x5.set_brightness(0.8)
+
+x = 0
+y = 50.0
+
+toggled = False
+
+while True:
+    up, down, left, right, switch, state = trackball.read()
+
+    # Update x and y vals based on movement
+    y += up
+    y -= down
+    x += right / 10.0
+    x -= left / 10.0
+
+    # Clamp to min of 0 and max of 100
+    x %= 100
+    y = max(0, min(y, 100))
+
+    # Calculate hue and brightness
+    h = x / 100.0
+    v = y / 100.0
+
+    # Prevents button from retriggering
+    debounce = 0.5
+
+    # Change toggled state if switch is pressed
+    if state and not toggled:
+        toggled = True
+        time.sleep(debounce)
+    elif state and toggled:
+        toggled = False
+        time.sleep(debounce)
+
+    # Set brightness to zero if switch toggled
+    if toggled:
+        v = 0
+
+    # Calculate RGB vals
+    w = 0
+    r, g, b = [int(c * 255) for c in colorsys.hsv_to_rgb(h, 1.0, v)]
+
+    # Set LEDs
+    trackball.set_rgbw(r, g, b, w)
+    rgbmatrix5x5.set_all(r, g, b)
+    rgbmatrix5x5.show()
+
+    time.sleep(0.01)