Replaces all dark-Mocha colours (#1e1e2e base, #313244 surface0, etc.) with the noticeably brighter Frappé variants (#303446 base, #414559 surface0, etc.) across the QSS and every hardcoded colour in Python source files (syntax highlighter, completer popup, log viewer, explain view, table viewer, schema browser, icons, etc.). Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>