Fix/pi fast boot

[Tanchouteur]

This pull request implements significant improvements to the fast boot optimization process and the application startup sequence, with a focus on making systemd integration more robust and startup health reporting more precise. The changes also enhance documentation and clarify best practices for Raspberry Pi 5 boot optimization. The most important changes are grouped below:

Fast Boot Optimization and Systemd Integration:

• Refactored the fast boot step in install.sh to present each optimization (background services, kiosk mode without LightDM, and cloud-init disabling) as separate, reversible options, with explicit tracking of which optimizations were applied or skipped. Added helper functions to safely disable systemd units only if present, and improved user messaging for each step. Summary of applied/skipped optimizations is shown at the end, along with restoration instructions. [1][2][3][4][5]
• Updated clios.service systemd unit to use Type=notify, enabling reliable notification to systemd when the application is fully ready. Increased startup timeout and set NotifyAccess=all.

Application Startup Health and Notification:

• Added precise startup phase reporting and health marker writing in main.py, including atomic file writes, elapsed time measurement, and phase logging. Integrated systemd READY=1 notification using a custom socket implementation, ensuring systemd only marks the service as ready after the first QML frame is displayed. [1][2][3][4][5][6][7][8]

Frontend Service Initialization:

• Deferred initialization of non-critical background tasks (network, system state, updater checks) in qt_bridge.py until after the first QML frame, to ensure the fastest possible visible startup and accurate health reporting. [1][2]

Documentation and Best Practices:

• Updated the Raspberry Pi 5 boot optimization guide to reflect the new fast boot process, clarify which services are affected, and discourage unvalidated overclocking. Added clear instructions for reversible changes and precise startup time measurement. [1][2][3][4][5]

Testing:

• Updated the test launcher to import the new startup phase tracking logic.

[Copilot]

Copilot was unable to review this pull request because the user who requested the review has reached their quota limit.