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

test_delivery_confirmation.md

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+# Delivery Confirmation Test Plan
+
+## Test Setup
+1. Build and run the bitchat app on two devices (or two instances on one device)
+2. Connect the devices and exchange nicknames
+
+## Test Cases
+
+### 1. Basic Delivery Confirmation
+- Send a private message from Device A to Device B
+- Expected: 
+  - Device A shows single gray checkmark (sent)
+  - When Device B receives, Device A shows double green checkmarks (delivered)
+  - Message IDs should match in logs
+
+### 2. Read Receipts
+- Device B opens/views the chat with Device A
+- Expected:
+  - Device A shows double blue checkmarks (read)
+  - Console logs show "Generating read receipt" and "Received READ receipt"
+
+### 3. Timeout Handling
+- Send a message to an offline peer
+- Expected:
+  - After 30 seconds, status changes to "Failed: Message not delivered"
+
+### 4. Message ID Consistency
+- Monitor console logs when sending messages
+- Expected:
+  - Message ID in "Tracking message" log matches ID in "Processing ACK" log
+  - No UUID mismatches
+
+## Debug Commands
+```bash
+# Filter delivery-related logs
+log stream --predicate 'processImagePath contains "bitchat"' | grep -E "(DeliveryTracker|Delivery|ACK|receipt)"
+
+# Check for message ID issues
+log stream --predicate 'processImagePath contains "bitchat"' | grep -E "(Tracking message|Processing ACK|message ID)"
+```
+
+## Known Working Flow
+1. Alice sends message to Bob (ID: abc123)
+2. Bob receives message and generates ACK
+3. Bob sends encrypted ACK back to Alice
+4. Alice receives and processes ACK, updates UI to "delivered"
+5. When Bob views chat, read receipt is sent
+6. Alice receives read receipt, updates UI to blue checkmarks