Cherry-pick: Fix MSSQL FK filter with case-sensitive collation (#1502)

[GingerAdonis]

Upstream PR

dimitri#1502

Summary

FK querying breaks on MSSQL databases with case-sensitive collation (e.g., SQL_Latin1_General_CP850_BIN2). Fix changes filter column references from lowercase kcu1 to uppercase KCU1 to match the SQL alias casing.

Files

• src/sources/mssql/mssql-schema.lisp

Notes

• Low risk, 4-line change
• Overlaps with PR fix: handle fetch-foreign-keys for mssql dimitri/pgloader#1243 (same fix) — either can be applied
• Priority: Lower — evaluate carefully