Reset OTA update modal after errors

[0xjc65eth]

Summary

• reset OTA upload progress when an update starts, fails, or the modal is dismissed
• show the existing Applying update state after upload completion while waiting for the response
• route Firmware and AxeOS error handling through a shared helper so non-fatal failures can be cleared by the user

Why

When an OTA upload hits a non-fatal error, the update modal can remain in a stale progress/error state because the observable error path does not run the complete handler. This makes recovery confusing and matches the user-facing behavior reported in #764.

Fixes #764.

Testing

• npm run build

[0xjc65eth]

Closing this for now to reduce maintainer review load, per feedback from @mutatrum. I am keeping #1705 open as the single focused PR because it is small, UI-only, and already has an ack. Happy to revisit this later only if maintainers ask for it. Thanks for the feedback and for maintaining the project.