frontend: Discard tray MAVLink listeners on destroy

[joaoantoniocardoso]

Summary

• HealthTray HEARTBEAT and GpsTrayMenu GPS listeners are stored with markRaw and discard()ed in beforeDestroy.
• Avoids stacking callbacks on shared MAVLink2Rest endpoints (and deep-observing Endpoint.latestData every frame).

Test plan

• Heartbeat icon and GPS trays still update normally
• Remount / HMR of App tray: listener count does not grow (no duplicate HEARTBEAT handling)
• No regression in armed state / GPS fix display

[github-actions]

Automated PR Review

0. Summary

• Verdict: LGTM

Cleans up MAVLink listeners for the Health and GPS tray menus by storing them (wrapped in markRaw so Vue 2.7 does not deep-observe the Listener → Endpoint.latestData chain) and calling listener.discard() in beforeDestroy. Prevents stacked HEARTBEAT/GPS callbacks and unnecessary per-frame deep-reactivity walks on component remount/HMR.

No further comments, nice job 👍

Generated by PR Review Bot. This is advisory, a human reviewer must still approve.

[joaoantoniocardoso]

Superseded by #4046 (same changes, head moved to fork joaoantoniocardoso/BlueOS-docker).

[joaoantoniocardoso]

Closed in favor of #4046.