ls425: Make acq process robust to serial read errors

[ykyohei]

Description

Implement auto reconnection to ls425 agent,

Motivation and Context

satp3 ls425 had intermittent usb connection issue.

2025-09-10T15:58:15+0000 acq:1 CRASH: [Failure instance: Traceback: <class 'serial.serialutil.SerialException'>: device reports readiness to read but returned no data (device disconnected or multiple access on port?)
2025-09-10T16:04:49+0000 acq:4 CRASH: [Failure instance: Traceback: <class 'serial.serialutil.SerialException'>: write failed: [Errno 5] Input/output error

How Has This Been Tested?

tested at satp3 and confirmed that it successfully reconnect.

2025-09-10T22:03:21+0000 acq:1 Status is now "running".
2025-09-11T15:17:53+0000 Decive reports readiness to read but returned no data. Reconnect to LS425.
2025-09-11T15:17:53+0000 Could not connect to LS425. Retrying after 30 sec...
2025-09-11T15:18:23+0000 Connected to LS425
2025-09-11T15:19:53+0000 Decive reports readiness to read but returned no data. Reconnect to LS425.
2025-09-11T15:19:53+0000 Connected to LS425
2025-09-11T15:20:26+0000 Decive reports readiness to read but returned no data. Reconnect to LS425.
2025-09-11T15:20:26+0000 Could not connect to LS425. Retrying after 30 sec...
2025-09-11T15:20:56+0000 Connected to LS425

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.

[BrianJKoopman]

Thanks for the PR! Great to see additional connection robustness upgrades. I'd just like to see more specific error handling for the connection dropout, otherwise looks good.

[BrianJKoopman]

Looks great, thanks for the updates!