Fix connect/disconnect/connect pattern on initial connection

- Added duplicate connection detection in key exchange handler
- When same peer connects through multiple peripherals, keep only one
- Track intentional disconnects to suppress disconnect messages
- Don't show disconnect message when dropping duplicate connections
- This prevents the confusing connect/disconnect/connect pattern

The issue was that both devices try to connect to each other simultaneously,
creating duplicate connections. One gets dropped, but now it's handled gracefully.

connection_fixes.md

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+# Connection Stability Fixes for BluetoothMeshService
+
+## Issues Causing Disconnect/Reconnect
+
+1. **Simultaneous Connection Attempts**: Both devices acting as central and peripheral can create duplicate connections
+2. **Temporary ID Management**: Using peripheral UUIDs as temporary IDs causes confusion
+3. **Premature State Updates**: Peer list updates happen before connections are fully established
+4. **Aggressive Disconnect Handling**: Peers are removed immediately on disconnect without grace period
+
+## Recommended Fixes
+
+### 1. Implement Connection Deduplication
+- Track ongoing connection attempts by peer ID
+- Reject duplicate connections from same peer
+- Use deterministic logic to decide which side maintains connection (e.g., compare peer IDs)
+
+### 2. Improve Peer State Management
+- Add connection states: CONNECTING, CONNECTED, DISCONNECTING
+- Only show "joined" after key exchange AND announce received
+- Add grace period before showing "left" messages (e.g., 5 seconds)
+
+### 3. Fix Temporary ID Handling
+- Don't add temp IDs to activePeers
+- Only update peer lists after receiving real peer ID
+- Use a separate pendingPeripherals dictionary
+
+### 4. Consolidate Key Exchange and Announce
+- Send key exchange and announce as atomic operation
+- Wait for both before considering peer "connected"
+- Add sequence numbers to prevent duplicate processing
+
+### 5. Add Connection Stability Timer
+- Don't show "joined" until connection stable for 1 second
+- Buffer rapid connect/disconnect cycles
+- Implement exponential backoff for reconnection attempts
+
+## Implementation Priority
+1. Fix duplicate connection handling (highest impact)
+2. Add connection grace period
+3. Improve state management
+4. Consolidate initialization messages