Add configurable hardware-information splash after startup artwork

[PurpleSentinel]

Parent: #43

Summary

Add a second startup splash immediately after the existing Caterham artwork. The first splash and the new hardware-information splash should each default to two seconds, with independent durations stored in the existing system configuration file.

Existing configuration

params.json already owns system-level configurable values including selectable durations, display timing, colours, firmware version, and the legacy BOOT_DELAY_SEC. Replace that ambiguous key with a clearly named first-splash duration and add a separate hardware-splash duration. Continue accepting BOOT_DELAY_SEC as a backward-compatible alias for existing installations.

Startup sequence

1. Render the existing artwork/text fallback and show it for the configured first-splash duration.
2. Render the hardware-information screen and show it for its independently configured duration.
3. Continue with IMU initialization and the Ready screen.

Hardware-information content

The second splash should present concise, readable device information gathered at runtime where possible:

• supported board/model and device type
• CPU or machine type
• Track Session Timer firmware version
• operating system/runtime name and version
• platform identifier

Values must be normalized or shortened so every line fits the 240×240 circular display. Missing runtime fields should use a safe Unknown fallback rather than preventing startup.

Acceptance criteria

• Add canonical STARTUP_SPLASH_DURATION_SEC and HARDWARE_SPLASH_DURATION_SEC values to params.json, both defaulting to 2.
• Validate both durations as non-negative numbers.
• Accept legacy BOOT_DELAY_SEC as the first-splash duration when the canonical key is absent.
• Display the existing first splash for exactly its configured duration.
• Display a second hardware-details splash for exactly its configured duration.
• Derive OS/runtime and machine details safely from MicroPython without coupling host tests to physical hardware.
• Keep all hardware-detail lines inside the circular display and use the native-resolution font.
• Add host tests for configuration defaults, legacy compatibility, missing runtime data, layout, display order, and timing.
• Update README, user guide, and deployment instructions.
• Validate both splashes and the reported values on the supported physical device.

Relationship

This is a focused startup-diagnostics deliverable beneath #43. A full interactive self-test remains tracked by the parent issue.