Add debugging and fix read receipts for messages without delivery status

- Add detailed logging to track read receipt generation
- Handle messages that don't have delivery status (older messages)
- Send read receipts for all unread messages when opening chat

DELIVERY_CONFIRMATION_SUMMARY.md

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+# Delivery Confirmation Feature Summary
+
+## Overview
+This branch implements a complete delivery confirmation system for bitchat, providing visual feedback for message delivery status and read receipts.
+
+## Key Components Implemented
+
+### 1. Delivery Status Tracking
+- **DeliveryTracker.swift**: Core service managing delivery confirmations
+  - Tracks pending deliveries with timeouts (30s for private, 60s for rooms)
+  - Handles retries for favorite peers (up to 3 attempts)
+  - Thread-safe implementation with proper lock management
+
+### 2. Protocol Updates
+- **BitchatProtocol.swift**: 
+  - Added `DeliveryStatus` enum with states: sending, sent, delivered, read, failed
+  - Added `DeliveryAck` structure for acknowledgments
+  - Added `ReadReceipt` structure for read confirmations
+  - New message types: `.deliveryAck` and `.readReceipt`
+
+### 3. UI Implementation
+- **ContentView.swift**:
+  - Added `DeliveryStatusView` component showing:
+    - Gray circle (○) for sending
+    - Gray checkmark (✓) for sent
+    - Green double checkmarks (✓✓) for delivered
+    - Blue double checkmarks (✓✓) for read
+    - Red triangle (⚠) for failed
+  - Proper vertical alignment with message text
+
+### 4. Message Flow
+- **BluetoothMeshService.swift**:
+  - Added ACK generation and sending
+  - Added read receipt generation when viewing chats
+  - Encrypted ACKs for privacy
+  - Proper message ID handling
+
+### 5. Critical Bug Fixes
+
+#### Deadlock Fix
+- **Issue**: macOS app freeze when sending private messages
+- **Cause**: Nested lock acquisition in DeliveryTracker
+- **Fix**: Restructured code to release locks before calling methods that acquire the same lock
+
+#### Message ID Preservation
+- **Issue**: ACKs referenced wrong message IDs
+- **Cause**: BinaryProtocol was reading but discarding ID with `let _ =`
+- **Fix**: Changed to `let id =` and passed ID to BitchatMessage constructor
+
+## Technical Details
+
+### Privacy Considerations
+- ACKs and read receipts are encrypted end-to-end
+- Only the original sender can decrypt and process them
+- No message content is included in confirmations
+
+### Performance
+- Debounced UI updates (100ms)
+- Efficient lock usage to prevent deadlocks
+- Automatic cleanup of old delivery data
+
+### Error Handling
+- Graceful timeout handling
+- Retry logic for favorites
+- Clear failure messages
+
+## Testing
+See `test_delivery_confirmation.md` for comprehensive test plan.
+
+## Future Enhancements
+- Group read receipts (show who read in rooms)
+- Delivery timestamps in UI
+- Persistent delivery status across app restarts
+- Network quality indicators