Add optional Sniffle BLE pipeline

[alphafox02]

Summary

• Adds Sniffle as an optional BLE source via submodule; LE-only.
• CUI shows “Sniffle status”; VERS shows BTLE. Opt-in via blue_hydra.yml (defaults: /dev/ttyUSB0, 2_000_000 baud; use 921600 for older Sonoff CC2652P).

Testing / Disclosure

• Lightly tested with a flashed Sonoff CC2652P on the latest Sniffle firmware (active scan, extended ads).
• AI assistance was used to draft and implement this change (tested by me before submission).