Summary

• add [IMAGE:/absolute/path.png] markers for conductor output sent through the Discord bridge
• upload marked files to Discord as attachments with discord.File while keeping normal text output unchanged
• reuse the same Discord output helper for both normal conductor replies and heartbeat alerts

Testing

• /opt/homebrew/bin/go test ./internal/session -run 'TestBridgeTemplate_Discord(ImageUploadSupport|HeartbeatNotification|TypingIndicator)'
• python3 -m py_compile ~/.agent-deck/conductor/bridge.py
• direct local helper check for text + image marker sequencing using a temporary PNG

Notes

• image markers currently expect an absolute local path, for example [IMAGE:/tmp/screenshot.png]
• the running local bridge has also been updated and restarted for verification