Improve BLE mesh reliability for large transfers (#964)

* Improve BLE mesh reliability for large transfers

Major reliability improvements for fragment-based transfers (photos, files):

**Notification Queue Fixes**
- Fix silent packet loss when notification queue is full - now queues for retry
- Fix retry queue bug where remaining items were lost when one retry failed
- Add periodic drain mechanism as backup (every 5 seconds)

**Write Queue Fixes**
- Fix drainPendingWrites to use atomic take-send-requeue pattern
- Add logging when peripheral is ready for more writes
- Add periodic drain for pending writes as backup

**Fragment Pacing**
- Increase fragment spacing from 4-5ms to 25-30ms to prevent buffer overflow
- Conservative pacing prevents packet loss on congested BLE connections

**Thread Safety**
- Fix race conditions in stopServices() and emergencyDisconnectAll()
- Synchronize access to peripherals/centrals dictionaries during cleanup
- Clear pending message queues in emergencyDisconnectAll()

**Error Recovery**
- Add handlers for all BLE state transitions (poweredOff, unauthorized, etc.)
- Clear Noise session and re-initiate handshake on decryption failure
- Queue ACKs/receipts for delivery after handshake instead of dropping
- Re-queue failed pending messages for retry

**Other Improvements**
- Add route freshness validation in MeshTopologyTracker (60s threshold)
- Add TTL (24h) and size limits (100 per peer) for MessageRouter outbox
- Fix connection timeout to check peripheral.state before canceling
- Add NoiseEncryptionService.clearSession(for:) method

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* Fix race condition and increase test timeouts

- Fix race in sendNoisePayload: use sync barrier instead of async
  to ensure payload is queued before initiating handshake
  (addresses Codex review feedback)

- Increase BLEServiceTests sleep from 0.5s to 1.0s for CI reliability

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

---------

Co-authored-by: jack <jackjackbits@users.noreply.github.com>
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

bitchatTests/BLEServiceTests.swift

@@ -73,7 +73,7 @@ struct BLEServiceTests {
             service.sendMessage("Hello, world!")
             
             // Allow async processing
-            try await sleep(0.5)
+            try await sleep(1.0)
         }
         #expect(service.sentMessages.count == 1)
     }
@@ -97,7 +97,7 @@ struct BLEServiceTests {
             )
             
             // Allow async processing
-            try await sleep(0.5)
+            try await sleep(1.0)
         }
         #expect(service.sentMessages.count == 1)
     }
@@ -113,7 +113,7 @@ struct BLEServiceTests {
             service.sendMessage("@alice @bob check this out", mentions: ["alice", "bob"])
             
             // Allow async processing
-            try await sleep(0.5)
+            try await sleep(1.0)
         }
     }
     
@@ -146,7 +146,7 @@ struct BLEServiceTests {
             service.simulateIncomingMessage(incomingMessage)
             
             // Allow async processing
-            try await sleep(0.5)
+            try await sleep(1.0)
         }
     }
     
@@ -189,7 +189,7 @@ struct BLEServiceTests {
             service.simulateIncomingPacket(packet)
             
             // Allow async processing
-            try await sleep(0.5)
+            try await sleep(1.0)
         }
     }
     
@@ -231,7 +231,7 @@ struct BLEServiceTests {
             service.sendMessage("Test delivery")
             
             // Allow async processing
-            try await sleep(0.5)
+            try await sleep(1.0)
         }
     }
     
@@ -273,7 +273,7 @@ struct BLEServiceTests {
             service.simulateIncomingPacket(packet)
             
             // Allow async processing
-            try await sleep(0.5)
+            try await sleep(1.0)
         }
     }
 }