Keep calibration delete result alive

[BenJule]

Summary

Keep the selected calibration history result alive for the asynchronous delete callback.

Root cause

The delete button callback captured the range-for variable result by reference. The callback runs after sync_history_data() has returned, so that reference can outlive the loop variable and access invalid state.

The neighboring edit callback already captures the same result by value.

Change

Capture result by value in the delete callback so every row retains its own stable calibration result.

Validation

• verified the unsafe reference capture is gone
• verified delete and edit callbacks both retain result copies
• git diff --check
• targeted CaliHistoryDialog.cpp syntax check when a matching compile database entry is available
• one GPG-signed commit

No local full build was performed. Full application validation remains delegated to Jenkins.