Fix theme-independent login styling and improve calendar responsiveness

- Remove theme reset on logout to preserve user theme preferences
- Implement hardcoded login page colors that override all theme styles
- Add comprehensive overrides for Google theme affecting login forms
- Optimize month view to show minimum required weeks (4-6) instead of fixed 6
- Implement dynamic calendar grid height calculations for better responsive fit
- Add calendar header to print preview with updated height calculations
- Update responsive breakpoints with proper header height variables

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

frontend/print-preview.css

@@ -212,6 +212,7 @@
     display: none !important;
 }
 
+
 /* Remove today highlighting in preview */
 .print-preview-paper .calendar-day.today,
 .print-preview-paper .week-day-header.today,