Remove debug code from Bluetooth power mode change handler

[Copilot]

Removes temporary debug instrumentation from Bluetooth::onPowerModeChanged that was added during development. The debug code included unsafe array indexing with powerStateNames[currentState] that could cause undefined behavior if invalid PowerState values were passed.

Changes:

• Removed powerStateNames array and all associated printf debug statements
• Removed temporary variables (deviceStr, bSuccess) used only for debug logging
• Removed unused else clause for unhandled power state transitions

Before:

static const char* powerStateNames[] = { ... };
printf("*** _DEBUG: Bluetooth::onPowerModeChanged: %s --> %s\n", 
       powerStateNames[currentState], powerStateNames[newState]);
// ... 9 more debug printf statements

After:

void Bluetooth::onPowerModeChanged(...) {
    if ((POWER_STATE_ON == currentState || POWER_STATE_UNKNOWN == currentState) && ...) {
        JsonArray connectedDevices = getConnectedDevices();
        // Production logic without debug noise
    }
}

Also added .gitignore to exclude build artifacts.

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