[Test Firmware] - Update README.md

[TuEmb]

[Copilot's Generation]

This pull request significantly improves the omi/firmware/test/README.md by restructuring and expanding the documentation for testing the OMI EVT board firmware. The new version organizes command references by subsystem, provides clearer instructions, adds detailed command tables with examples and notes, and introduces a quick test sequence for validating all peripherals.

Key improvements include:

Documentation Structure and Clarity

• Reorganized the README to group commands by hardware subsystem (BLE, WiFi, Battery, Flash, IMU, Microphone, LED, Button, Motor, SD Card, System), making it easier to find relevant information. Added clear section headers and thematic dividers.
• Expanded command tables to include example usages, expected outputs, and detailed notes for each command, improving usability for new users.

Expanded Content and Usability

• Added a comprehensive "Quick Test Sequence" section providing a recommended order of commands to validate all major peripherals, streamlining the bring-up and verification process.
• Included additional context and notes for each subsystem (e.g., LED index mapping, SD card filesystem details, power management behavior), helping users understand expected behaviors and requirements.

Consistency and Accuracy

• Updated terminology for consistency (e.g., "System OFF" commands now use sys off

[gemini-code-assist]

Code Review

This pull request provides a significant and high-quality update to the README.md for the test firmware. The documentation is now exceptionally well-structured, grouping commands by subsystem, which greatly enhances clarity and ease of use. The addition of detailed command tables with examples, expected outputs, and explanatory notes is a fantastic improvement. The new 'Quick Test Sequence' is a valuable asset for developers, providing a straightforward way to validate all peripherals. The accuracy of the documentation has also been improved, correcting previous inaccuracies and adding important details, such as the distinction between absolute and relative paths for SD card commands. Overall, this is an excellent contribution that significantly improves the developer experience for testing the OMI EVT board.

[beastoin]

lgtm @TuEmb