Continuous Integration for Multi-Board Validation

[AmmarOkla12772]

Establish automated build validation for SampleX board support packages to prevent regressions as new boards are added.

Initial pipeline requirements:

• Build STM32F401RE BSP
• Build Raspberry Pi Pico 2 W BSP
• Validate all demo applications
• Verify CMake configuration
• Catch compilation and linker regressions
• Validate generated firmware artifacts

DoD:

• GitHub Actions workflow
• Build status reporting
• CI documentation
• Board build matrix