feat: Add BLE beacon advertising example.

[nedseb]

Target repository

This example should be created in micropython-steami-sample, not in micropython-steami-lib. BLE examples are not tied to a specific driver and belong in the sample repo.

What

Create an example that broadcasts a BLE beacon advertisement containing the board's name and a sensor reading (e.g. temperature).

Why

First step in the BLE + indoor localization learning path. Teaches aioble advertising basics. The beacon is visible from any BLE scanner app (nRF Connect, LightBlue).

Suggested approach

1. Initialize BLE with bluetooth.BLE() and aioble
2. Read a sensor value (temperature or distance)
3. Build an advertising payload with the device name + sensor data as manufacturer-specific data
4. Advertise in a loop, updating the sensor value periodically
5. Display the advertised data on the OLED for visual feedback

Hardware

• STM32WB55 BLE radio
• SSD1327 OLED (for display)
• Any I2C sensor (WSEN-PADS, HTS221, VL53L1X, etc.)

References

• Existing BLE examples in steamicc/micropython-steami-sample/BLE/
• aioble documentation: https://github.com/micropython/micropython-lib/tree/master/micropython/bluetooth/aioble

[nedseb]

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