Use ESP_PWR_LVL_P9 enum for BLE TX power

[Copilot]

NimBLEDevice::setPower(9) used a raw integer which is ambiguous — in ESP-IDF the esp_power_level_t enum indices don't map 1:1 to dBm values, so 9 does not mean +9 dBm at the ESP-IDF layer.

Change

• src/sp140/ble/ble_core.cpp: Replace setPower(9) with setPowerLevel(ESP_PWR_LVL_P9), using the enum-based API available in NimBLE-Arduino v2.x on ESP32 platforms.

// Before
NimBLEDevice::setPower(9);

// After
NimBLEDevice::setPowerLevel(ESP_PWR_LVL_P9);

ESP_PWR_LVL_P9 is the correct esp_power_level_t constant for +9 dBm and makes the intent unambiguous.

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