Add Pac-Man power-on flow and document Odin integration

- Add a four-second arcade-style boot sequence followed by the
  Character / Nickname introduction.
- Separate cabinet power-on from RFID credit and player Start.
- Add operator Power on control and cabinet power-state reporting.
- Prevent repeated power commands from restarting boot or gameplay.
- Ignore RFID scans received before the cabinet is ready.
- Add power-state, RFID, controller, and GPIO feedback regression tests.

- Expand the master walkthrough with export, packaging, file transfer,
  fresh-Pi setup, RFID compilation, and end-to-end testing instructions.
- Correct tester hardware documentation: BCM23/J20 drives an LED;
  physical buttons connect through a separate I2C1 input board.
- Document operator-triggered power-on as the current test workflow
  and retain the temporary 2.4 configuration compatibility notes.
- Record successful physical testing of power-on, RFID credit,
  and player Start.

- Add an Odin integration README describing the proposed Rust/NATS
  bridge, shared messages, Flutter GM interface, autopilot sequencing,
  hardware ownership, and Starfish SSH-management role.
- Define migration milestones and information needed from the
  framework owner; link the integration guide from the root README.

Validation: 69 controller tests, 10 GPIO tests, Pac-Man power/RFID
checks, managed-cabinet lifecycle checks, and visual screen inspection.

tests/pcb/render_pacman_power.gd.uid

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+uid://b72d387gge7x7