build: add compile validation workflow

[fjoelnr]

Summary

• add a compile-only PlatformIO validation path with temporary config handling
• declare required PlatformIO libraries and modernize ESP sleep includes for current frameworks
• add a GitHub Actions firmware build workflow and document the new validation path

Verification

• python -m platformio --version
• python scripts/compile_check.py

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly enhances the firmware's build and validation process by introducing a dedicated compile-only workflow. This change streamlines development by providing a consistent and automated way to verify compilation without needing a full hardware setup, improving the reliability and maintainability of the codebase.

Highlights

• Compile Validation Workflow: A new compile-only PlatformIO validation path has been introduced, including a Python script (scripts/compile_check.py) that handles temporary config.h files, ensuring that the firmware can be compiled without requiring a local configuration.
• PlatformIO Library Declarations: Required PlatformIO libraries, specifically PubSubClient and SparkFun BME280, have been explicitly declared in platformio.ini to ensure consistent build environments.
• ESP Sleep API Modernization: The ESP sleep includes and function calls have been updated to use the more modern <esp_sleep.h> header and corresponding API (esp_sleep_wakeup_cause_t, esp_sleep_get_wakeup_cause, esp_sleep_enable_timer_wakeup).
• Documentation Updates: The README.md, docs/STATUS.md, docs/operations.md, and docs/verification.md files have been updated to reflect the new compile validation process and the status of CI/build validation.

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Ignored Files

• Ignored by pattern: .github/workflows/** (1)
  • .github/workflows/build.yml

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[gemini-code-assist]

Code Review

This pull request introduces a valuable compile validation workflow, making the build process more robust and CI-friendly. The changes include a new Python script for handling temporary configurations, explicit dependency declarations in platformio.ini, and updates to the documentation. Additionally, the ESP32 sleep API usage has been modernized. My review identified one high-severity issue in src/main.cpp where the API modernization inadvertently introduced a bug in downstream logic. The rest of the changes are well-implemented and significantly improve the project's structure.

[gemini-code-assist]

While updating the sleep API is a good modernization step, changing the type to esp_sleep_wakeup_cause_t and the function to esp_sleep_get_wakeup_cause() introduces a bug in the switch statement on lines 54-62. This statement uses hardcoded integer values (magic numbers) which are no longer correct, as the enum values for esp_sleep_wakeup_cause_t differ from the old API.

To fix this and improve code clarity, the switch statement should use the symbolic enum members instead of magic numbers. For example:

switch(wakeup_reason)
{
  case ESP_SLEEP_WAKEUP_TIMER: 
    Serial.println("Wakeup caused by timer"); 
    break;
  // ... other cases using enum members
  default: 
    Serial.println("Wakeup reason: " + String(wakeup_reason)); 
    break;
}