feat: initialize ESP32 project with PlatformIO

[Tonyfudecai]

Description

Set up the initial embedded project structure for MicroClaw using PlatformIO (ESP32).

Requirements

• platformio.ini with ESP32 board configuration
• src/main.cpp with basic WiFi + MQTT setup
• lib/ directory for sensor drivers
• .gitignore for PlatformIO build artifacts
• README with flash instructions

Skills

C/C++, PlatformIO, ESP32

[Jorel97]

Submitted PR #12 for this as part of an integrated ESP32-C3 MicroClaw port: #12

This covers the PlatformIO project setup, ESP32-C3 target config, main firmware loop, README flash instructions, and keeps generated PlatformIO artifacts ignored. Validation: platformio run -e esp32c3,
ode scripts/validate-esp32-port.mjs,
ode --check scripts/validate-esp32-port.mjs, and git diff --check.