Fix day number color inheritance for today and selected in print

The day numbers for today and selected dates were not matching the
appearance of normal day numbers in print preview due to color
inheritance issues.

Changes:
- Remove color override from .calendar-day.today parent element
- Use color: inherit on day numbers to get default text color
- Use font-weight: 600 to match standard day number styling

Now all day numbers appear uniform in print preview regardless of
today/selected state.

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

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

frontend/print-preview.css

@@ -234,14 +234,13 @@
 .print-preview-paper .week-day-column.today {
     background-color: transparent !important;
     border: 1px solid var(--calendar-border, #f0f0f0) !important;
-    color: var(--text-color, #333) !important;
     font-weight: normal !important;
     box-shadow: none !important;
 }
 
 .print-preview-paper .calendar-day.today .day-number {
-    color: var(--text-color, #333) !important;
+    color: inherit !important;
-    font-weight: normal !important;
+    font-weight: 600 !important;
 }
 
 /* Remove selected day highlighting in preview */
@@ -252,8 +251,8 @@
 }
 
 .print-preview-paper .calendar-day.selected .day-number {
-    color: var(--text-color, #333) !important;
+    color: inherit !important;
-    font-weight: normal !important;
+    font-weight: 600 !important;
 }
 
 /* Week view hour range filtering in preview - target all possible selector paths */