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/spirit-level/spirit-level.py

@@ -0,0 +1,107 @@
+#!/usr/bin/env python3
+
+from PIL import Image, ImageDraw, ImageFont, ImageFilter
+import math
+import msa301
+import ST7789 as ST7789
+
+print("""This Pimoroni Breakout Garden example requires an
+MSA301 3DoF Motion Sensor Breakout and a 1.3" LCD Breakout.
+
+This examples emulates a circular spirit level, using the
+LCD to draw the spirit level and the accelerometer to
+detect orientation.
+
+Press Ctrl+C to exit.
+""")
+
+# Set up LCD
+disp = ST7789.ST7789(
+    port=0,
+    cs=ST7789.BG_SPI_CS_FRONT,
+    dc=9,
+    backlight=19,
+    spi_speed_hz=80 * 1000 * 1000
+)
+
+WIDTH = disp.width
+HEIGHT = disp.height
+
+disp.begin()
+
+# Load the image assets
+level = Image.open("images/spirit-level.png").convert("RGBA")
+bubble = Image.open("images/spirit-level-bubble.png").convert("RGBA")
+crosshair_black = Image.open("images/spirit-level-crosshair-black.png").convert("RGBA")
+crosshair_red = Image.open("images/spirit-level-crosshair-red.png").convert("RGBA")
+
+# Sizes/coordinates of things
+bubble_dia = 64
+bubble_rad = bubble_dia / 2
+circle_dia = 190
+circle_rad = circle_dia / 2
+border = (WIDTH - circle_dia) / 2
+
+centre_x = WIDTH / 2
+centre_y = HEIGHT / 2
+
+# Set up MSA301
+accel = msa301.MSA301()
+accel.set_power_mode('normal')
+
+x_vals = []
+y_vals = []
+
+smooth = 3
+
+while True:
+    # Read MSA301 values
+    x, y, z = accel.get_measurements()
+
+    # z = x-axis, y = y-axis
+    bubble_centre_x = (2 - (z + 1)) * (circle_dia / 2) + border
+    bubble_centre_y = (y + 1) * (circle_dia / 2) + border
+
+    # Work out vector length to check if outside circle
+    delta_x = bubble_centre_x - centre_x
+    delta_y = bubble_centre_y - centre_y
+
+    vector_length = math.sqrt(delta_x ** 2 + delta_y ** 2)
+
+    # If outside circle, scale position back down relatively
+    if vector_length > circle_rad - bubble_rad:
+        scale = (circle_rad - bubble_rad) / vector_length
+        bubble_centre_x = centre_x + delta_x * scale
+        bubble_centre_y = centre_y + delta_y * scale
+
+
+    # Average x and y values to smooth jitter
+    x_vals.append(bubble_centre_x)
+
+    if len(x_vals) > smooth:
+        x_vals = x_vals[1:]
+
+    bubble_centre_x = int(sum(x_vals) / len(x_vals))
+
+    y_vals.append(bubble_centre_y)
+
+    if len(y_vals) > smooth:
+        y_vals = y_vals[1:]
+
+    bubble_centre_y = int(sum(y_vals) / len(y_vals))
+
+
+    # Use red crosshair if bubble is close to centre
+    if (-0.05 < z < 0.05) and (-0.05 < y < 0.05):
+        crosshair = crosshair_red
+    else:
+        crosshair = crosshair_black
+
+    # Construct image
+    image = Image.new('RGBA', (WIDTH, HEIGHT), color=(0, 0, 0, 0))
+    image.paste(level, (0, 0))
+    image.paste(bubble, (int(bubble_centre_x - (bubble_dia / 2)), int(bubble_centre_y  - (bubble_dia / 2))), mask=bubble)
+    image.paste(crosshair, (0, 0), mask=crosshair)
+
+    # Display on LCD
+    disp.display(image)