docs: add Indonesian ESP32 + HC-SR04 WebSocket end-to-end guide

[musfaagv]

Motivation

• Provide a step-by-step, local-language guide so users can run the full ESP32 → WebSocket server → Web UI loop with HC‑SR04 ultrasonic sensor.
• Reduce setup friction and support requests by documenting wiring, firmware config, server and web app steps, payload formats, and troubleshooting in one place.

Description

• Add example_firmware/PANDUAN_ESP32_WS_ULTRASONIC_ID.md, a comprehensive Indonesian guide covering architecture, prerequisites, wiring, firmware configuration, payload formats, and end-to-end validation steps.
• Add a cross‑reference link in example_firmware/README.md pointing to the new guide so it is easy to find from the example firmware docs.
• The guide includes exact commands to run the Python WebSocket relay (example_websocket_server), instructions to run the web app (npm install && npm run dev), and JSON examples for sensor and LED command payloads.

Testing

• Verified the new file content and README update by previewing with sed and nl -ba to ensure formatting and sections render correctly.
• Confirmed the new guide file exists in the repository tree via file listing commands and reviewed the inserted link in example_firmware/README.md.
• This is a documentation-only change and automated test suites were not required; validation checks completed successfully.

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Codex Task