build(bridge): Update meshcore-cli to version 1.3.12

Fix critical bug in private message logging that prevented proper DM tracking.

Previous version (1.3.11) logged sent private messages with incomplete data:
- Missing recipient information
- Only included sender name in 'name' field
- Format: {"type": "SENT_MSG", "name": "MarWoj", "text": "...", ...}

Updated version (1.3.12) includes both sender and recipient:
- Added 'recipient' field with recipient's device name
- Added 'sender' field with sender's name
- Format: {"type": "SENT_MSG", "recipient": "SP7UNR_tdeck", "sender": "MarWoj", "name": "SP7UNR_tdeck", ...}

This fix enables proper message tracking in the DM module, as it now correctly
identifies both parties in private message exchanges.

Fix requested from meshcore-cli maintainers and implemented in v1.3.12.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

meshcore-bridge/Dockerfile

@@ -13,7 +13,7 @@ RUN apt-get update && apt-get install -y \
     && rm -rf /var/lib/apt/lists/*
 
 # Install meshcore-cli (from PyPI)
-RUN pip install --no-cache-dir meshcore-cli
+RUN pip install --no-cache-dir meshcore-cli==1.3.12
 
 # Copy bridge application
 COPY requirements.txt .