fix: standardize date format to ISO 8601

[aniasse]

Summary

• Standardizes date format to ISO 8601 (YYYY-MM-DD) using en-CA locale
• Resolves ambiguity between MM/DD/YYYY (US) and DD/MM/YYYY (European) formats

Changes

• Updated Locale.datetime() to use en-CA locale instead of system default
• This ensures consistent, sortable, and unambiguous date output

Benefits

• Consistency: International standard ISO 8601
• Sortability: Lexicographically sortable
• Clarity: No ambiguity between US and European formats
• Interoperability: Better for APIs and data exchange

Testing

• Verified date output format is now YYYY-MM-DD

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

Fixes anomalyco#12398