Fix remaining and completion time when firmware ETA is zero

[FokiDoki]

Fixes the Remaining Time sensor staying at 0 and the Print Completion Time sensor staying unknown when Adventurer 5M firmware reports estimatedTime: 0 during an active print.

Parse the slicer duration suffix from the active G-code filename, such as 4h13m.

• When the firmware reports estimatedTime: 0, calculate remaining time as the slicer estimate minus elapsed print time.
• Fall back to elapsed time/progress when the filename does not contain a duration.
• Use the same estimate for Remaining Time and Print Completion Time.
• Ignore stale print data while the printer is idle.
• Add unit tests and update documentation.
• Bump the integration version to 1.3.5.

[GhostTypes]

Thank you for the detailed writeup and all of your work, however I don't think this is the correct way of fixing the problem.

FlashForge's firmware (unfortunately) looks for specific metadata which is not produced by regular OrcaSlicer or other similar slicers. This causes the printer's local API to not report back a value for estimated time, while the printer's screen itself calculates from the g-code directly and works fine.

In this state, there is not a truly accurate method to calculate the ETA.

I made a post-process script for OrcaSlicer (works for other slicers based on OrcaSlicer) which is available here to fix this issue, and will update the troubleshooting section of the readme to include this.

If you'd like to discuss this further or have any issues with the post-process script, feel free to reach out to me directly on discord (GhostTypes) or open an issue