fix: bind aware datetimes to local time zone columns

[skhe]

Summary

• Format aware Python datetime and time parameters with a space before their UTC offset, which DM8 requires for TIMESTAMP WITH LOCAL TIME ZONE columns.
• Add regression cases with positive and negative offsets, including cross-day values.
• Record the UTF-8 and GB18030 validation results and update the previous CI evidence.

Validation

• Before fix: both new cases failed with DM8 error 6015.
• Official ARM DM8 UTF-8: 168 passed, 2 deselected, 0 skipped.
• Official ARM DM8 GB18030: 168 passed, 2 deselected, 0 skipped.