Update AI rules and tighten the db-query skill

[tjementum]

Summary & Motivation

• Backend rule additions:
  • IgnoreQueryFilters calls must name the filter explicitly, e.g. .IgnoreQueryFilters([QueryFilterNames.SoftDelete]), not the bare overload.
  • Database migration filenames must include HHmm, not just yyyyMMdd, so migrations within the same day order deterministically.
  • Forbid #pragma warning disable CS#### — fix the warning instead.
• Require confirmation in the db-query skill before any mutating SQL (INSERT, UPDATE, DELETE, TRUNCATE, DROP).
• Use the explicit branch name when setting upstream after gh pr create — git push -u origin HEAD doesn't reliably configure tracking.

Checklist

• I have added tests, or done manual regression tests
• I have updated the documentation, if necessary

[linear]

PP-1207