Fix isBluetoothEnabled returning false on first call due to CBCentralManager async initialization

[Copilot]

CBCentralManager.state initializes asynchronously as .unknown and takes ~500ms to update. The previous implementation checked the state immediately without waiting, causing isBluetoothEnabled() to always return false on first call.

Changes

Implement CBCentralManagerDelegate

• Added CBCentralManagerDelegate protocol conformance
• Set delegate when initializing CBCentralManager(delegate: self, queue: nil)
• Cache state in centralManagerState property
• Implement centralManagerDidUpdateState(_:) to update cached state and resolve pending promises

Update isBluetoothEnabled logic

• Return immediately if state is already known (not .unknown)
• Queue callback in stateUpdateCallbacks array if state is .unknown
• Trigger lazy initialization to start async state update
• Resolve with cached state on subsequent calls (no performance impact)

Memory management

• Use weak self capture in callbacks to avoid retain cycles
• Resolve with false if self is deallocated before state updates

Example

// Before: Always false on first call
RNBluetoothClassic.isBluetoothEnabled()
  .then(r => console.log(r))  // false (even if BT is on)

// After: Waits for actual state, subsequent calls instant
RNBluetoothClassic.isBluetoothEnabled()
  .then(r => console.log(r))  // true (accurate, waits ~100ms)
  .then(() => RNBluetoothClassic.isBluetoothEnabled())
  .then(r => console.log(r))  // true (instant, cached)

Original prompt

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This section details on the original issue you should resolve

<issue_title>IsBluetoothEnabled always false on first call</issue_title>
<issue_description>Mobile Device Environment

• Device: iPad Mini (5th gen)
• OS: iPadOS 18.5

Application Environment
Provide information about your development environment:

• React Native version: 0.76.9
• RN Bluetooth Classic version: 1.73.0-rc.12

Describe the bug

1. Calling RNBluetoothClass.isBluetoothEnabled() always returns false on the first call, regardless of the actual bluetooth state. Calling the function twice in a row, via isBluetoothEnabled.finally(() => isBluetoothEnabled()) also always returns false on the first call. The only way i am able to actually get the proper bluetooth state, is by putting a short delay (~500ms) in between the function invocations, and only taking the last result.

To Reproduce
Steps to reproduce the behavior:

1. Create a basic app with the following code:

export const App = () => {
  useEffect(() => {
    RNBluetoothClassic.isBluetoothEnabled()
      .then((r) => console.log('bluetooth enabled: ', r))
      .then(() => new Promise((res) => setTimeout(res, 1000)))
      .then(() => RNBluetoothClassic.isBluetoothEnabled())
      .then((r) => console.log('bluetooth enabled now?: ', r))
  }, [])
  return <Text>My App</Text>
}

2. observe the following logs in the developer console:

bluetooth enabled: false
bluetooth enabled now?: true

Expected behavior
isBluetoothEnabled returns the proper response regardless of invocation timing.

</issue_description>

<agent_instructions>Need to determine if there is any documentation surrounding the call to the Apple CBCentralManagerState that would take a few moments to get the correct value. Or could there be an issue with the bridge handling resolution of promises between React JS and Native module?</agent_instructions>

Comments on the Issue (you are @copilot in this section)

@kenjdavidson This is really just a call through to ``` /** * Check the Core Bluetooth Central Manager for status */ private func checkBluetoothAdapter() -> Bool { var enabled = false

    if #available(iOS 10.0, *) {
        enabled = (cbCentral.state == CBManagerState.poweredOn)
    } else {
        enabled = (cbCentral.state.rawValue == CBCentralManagerState.poweredOn.rawValue)
    }
    
    return enabled
}

If something in the CBCentralManagerState takes a while to sort itself out.  Feel free to debug it and open a PR if you see what's up with it.

I'm pretty much hands off at this point, just accepting PRs and releasing, sometimes helping look through code and docs when time permits.</body></comment_new>
</comments>

• Fixes IsBluetoothEnabled always false on first call #359

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