Drop tuulbox dependency

[twyatt]

Tuulbox is transitively pulling in core-ktx causing undesirable version bumps (see #1206 for more details); because it is minimally used, dropping it entirely.

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Note

Low Risk
Small, behavior-aligned copy of existing Tuulbox code with no auth or data-path changes; main risk is drift if the upstream helper changes.

Overview
Removes the tuulbox-coroutines dependency from the version catalog, kable-core, and the sensortag Bluetooth sample to avoid transitive core-ktx version pressure.

Android Bluetooth state observation still uses broadcastReceiverFlow, but that helper is now an internal copy in kable-core (same callbackFlow + ContextCompat.registerReceiver with RECEIVER_NOT_EXPORTED), and BluetoothState.kt imports it from the local module instead of Tuulbox.

^{Reviewed by Cursor Bugbot for commit 2e7e88a. Configure here.}

[twyatt]

Closing in favor of #1243.