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/rainbow-compass/README.md

@@ -0,0 +1,28 @@
+# Rainbow compass example
+
+Calculates and displays compass heading as an
+RGB colour around the hue wheel, with North being red, South cyan,
+East green, and West purple, approximately.
+
+## Pre-requisites
+
+This example requires:
+
+- A Pimoroni [Breakout Garden](https://shop.pimoroni.com/products/breakout-garden-hat-i2c-spi)
+- A Pimoroni [LSM303D Motion Sensor Breakout](https://shop.pimoroni.com/products/lsm303d-6dof-motion-sensor-breakout)
+- A Pimoroni [5x5 RGB Matrix Breakout](https://shop.pimoroni.com/products/5x5-rgb-matrix-breakout)
+
+## Installation
+
+Pop the breakouts into your Breakout Garden, and then run the `install.sh` 
+script in the root of this repository with `sudo ./install.sh` to automagically 
+install all of the required libraries.
+
+## Running this example
+
+To run this example, type `./rainbow-compass.py` in the terminal, and then 
+walk through the calibration steps.
+
+Depending on the orientation of you LSM303D breakout, you can change the 
+line that says `Y = 2` in the `raw_heading` function to e.g. `Y = 1` if 
+you have the breakout flat rather than vertical.