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/heartbeat/README.md

@@ -0,0 +1,57 @@
+# Heartbeat example
+
+This example, the Pulse-O-Matic 6000, is a heartbeat plotter and BPM display.
+
+## Important!
+
+**This code should not be used for medical diagnosis, as the basis for a real smoke
+or fire detector, or in life-critical situations. It's for fun/novelty use only, 
+so bear that in mind while using it.**
+
+## Pre-requisites
+
+This example requires:
+
+- A Pimoroni [Breakout Garden HAT](https://shop.pimoroni.com/products/breakout-garden-hat-i2c-spi)
+- A Pimoroni [MAX30105 Breakout - Heart Rate, Oximeter, Smoke Sensor](https://shop.pimoroni.com/products/max30105-breakout-heart-rate-oximeter-smoke-sensor)
+- A Pimoroni [1.12" OLED Breakout (SPI)](https://shop.pimoroni.com/products/1-12-oled-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 the libraries to run the I2C breakouts.
+
+For this example you'll need to make sure some additional software is installed:
+
+```
+sudo apt install python3-pil
+```
+
+You'll need to clone and install the library for the 1.12" OLED Breakout (SPI)
+as follows:
+
+```
+git clone https://github.com/pimoroni/sh1106-python
+sudo ./install.sh
+```
+
+This example assumes that you have the OLED plugged into the front slot on the
+Breakout Garden HAT, which should also work with the Breakout Garden Mini HAT.
+To change it to the back slot, change `device=1` to `device=0` on the line
+where the OLED is set up.
+
+## Running this example
+
+To run this example, type `./heartbeat.py` in the terminal.
+
+It's best to hold the sensor against your fingertip (the fleshy side)
+using a piece of wire or a rubber band looped through the mounting
+holes on the breakout, as the sensor is very sensitive to small
+movements and it's hard to hold your finger against the sensor with
+even pressure.
+
+If you're using your MAX30105 Breakout with Breakout Garden, then
+we'd recommend using one of our 
+[Breakout Garden Extender Kits](https://shop.pimoroni.com/products/breakout-garden-extender-kit)
+with some [female to female jumper jerky](https://shop.pimoroni.com/products/jumper-jerky?variant=348491271).