Show Bluetooth permission alerts on launch and foreground (#765)

* Fix test suite peer ID collisions

Use unique peer IDs for each test suite to prevent global registry
collisions when Swift Testing runs suites in parallel.

- PrivateChatE2ETests: PRIV_* prefix
- PublicChatE2ETests: PUB_* prefix
- Update all peer ID references to use actual instance IDs

This fixes the race condition where simplePublicMessage() was receiving
duplicate deliveries due to registry contamination.

* Add Bluetooth permission & state alerts on launch and foreground

Wire up existing Bluetooth alert infrastructure to show notifications
when Bluetooth is off, unauthorized, or unsupported.

Changes:
- Add didUpdateBluetoothState() to BitchatDelegate protocol
- BLEService now notifies delegate when Bluetooth state changes
- ChatViewModel implements delegate method to show alerts
- Check Bluetooth state on app launch (after 100ms delay)
- Check Bluetooth state when app comes to foreground
- Add getCurrentBluetoothState() method to BLEService

The UI alert already existed but wasn't wired up. Now users will see
appropriate alerts for:
- Bluetooth turned off
- Bluetooth permission denied
- Bluetooth unsupported on device

Alert includes a button to open Settings on iOS.

---------

Co-authored-by: jack <jackjackbits@users.noreply.github.com>

bitchatTests/BLEServiceTests.swift

@@ -286,4 +286,7 @@ private final class MockBitchatDelegate: BitchatDelegate {
     func didUpdatePeerList(_ peers: [String]) {}
     func isFavorite(fingerprint: String) -> Bool { return false }
     func didUpdateMessageDeliveryStatus(_ messageID: String, status: DeliveryStatus) {}
+    func didReceiveNoisePayload(from peerID: String, type: NoisePayloadType, payload: Data, timestamp: Date) {}
+    func didUpdateBluetoothState(_ state: CBManagerState) {}
+    func didReceivePublicMessage(from peerID: String, nickname: String, content: String, timestamp: Date) {}
 }

bitchatTests/Fragmentation/FragmentationTests.swift

@@ -8,6 +8,7 @@
 
 import Testing
 import Foundation
+import CoreBluetooth
 @testable import bitchat
 
 struct FragmentationTests {
@@ -134,6 +135,7 @@ extension FragmentationTests {
         func isFavorite(fingerprint: String) -> Bool { false }
         func didUpdateMessageDeliveryStatus(_ messageID: String, status: DeliveryStatus) {}
         func didReceiveNoisePayload(from peerID: String, type: NoisePayloadType, payload: Data, timestamp: Date) {}
+        func didUpdateBluetoothState(_ state: CBManagerState) {}
         func didReceivePublicMessage(from peerID: String, nickname: String, content: String, timestamp: Date) {
             publicMessages.append((peerID, nickname, content))
         }