Add ESP32 series support

[Copilot]

The firmware was entirely ESP8266-specific. This PR makes it compile and run on ESP32, ESP32-S2, and ESP32-C3 by replacing or conditionally compiling all platform-specific code.

Platform abstraction

• defines.h: Replaced manual typedef declarations with <stdint.h>. Added a platform-independent getChipId() inline helper:

  #ifdef ESP32
  inline uint32_t getChipId() {
      uint32_t chipId = 0;
      for (int i = 0; i < 32; i += 8)
          chipId |= ((ESP.getEfuseMac() >> (32 - i)) & 0xff) << i;
      return chipId;
  }
  #else
  inline uint32_t getChipId() { return ESP.getChipId(); }
  #endif

• All ESP.getChipId() call sites updated to use getChipId().

Build environments

• platformio.ini: Added esp32-base, esp32s2-base, esp32c3-base environments (espressif32 platform, LittleFS filesystem). Moved platform and flash-mode settings into per-environment blocks.

Conditional includes & APIs

• HTTP client: ESP8266HTTPClient.h → HTTPClient.h on ESP32 (IRbaby.cpp, IRbabyIR.cpp, IRbabyOTA.cpp)
• WiFi: ESP8266WiFi.h → WiFi.h on ESP32 (IRbabyUDP.cpp, IRbabyMsgHandler.cpp, IRbabyUserSettings.cpp)
• OTA: ESPhttpUpdate / t_httpUpdate_return → httpUpdate / HTTPUpdateResult on ESP32
• Ticker: attach_scheduled() / attach_ms_scheduled() → attach() / attach_ms() (ESP32 Ticker lacks scheduled variants)

Filesystem & system APIs

• FSInfo64 / LittleFS.info64() → FSInfo / LittleFS.info() on ESP32
• clearBinFiles(): replaced Dir-based iteration (ESP8266-only) with File::openNextFile() on ESP32
• settingsClear(): ESP.eraseConfig() + ESP.reset() → WiFi.disconnect(true, true) + ESP.restart() on ESP32
• ESP.getFlashChipSpeed() / ESP.getResetReason() guarded under #ifdef ESP8266; ESP32 uses esp_reset_reason() from <esp_system.h> and returns "N/A" for flash speed

Device identity

• IRbabyha.cpp: device model field is now "ESP32" or "ESP8266" based on the compile target.