Fix timezone conversion bug for events displaying on wrong day

- Preserve original local dates when converting times to UTC for storage
- Prevent events created late in day from appearing on next day due to timezone offset
- Remove hacky bandaid logic in week view that tried to handle timezone shifts
- Use stored event date directly instead of calculating from UTC conversion
- Ensure events always display on intended day regardless of timezone

Fixes issue where events created within last 4 hours of day would show on wrong day
after UTC conversion caused date component to shift to next day.

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

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

frontend/src/components/event_form/types.rs

@@ -164,17 +164,20 @@ impl EventCreationData {
                 self.end_time.format("%H:%M").to_string(),
             )
         } else {
-            // Convert local date/time to UTC
+            // Convert local date/time to UTC, but preserve original local dates
             let start_local = Local.from_local_datetime(&self.start_date.and_time(self.start_time)).single();
             let end_local = Local.from_local_datetime(&self.end_date.and_time(self.end_time)).single();
             
             if let (Some(start_dt), Some(end_dt)) = (start_local, end_local) {
                 let start_utc = start_dt.with_timezone(&chrono::Utc);
                 let end_utc = end_dt.with_timezone(&chrono::Utc);
+                
+                // IMPORTANT: Use original local dates, not UTC dates!
+                // This ensures events display on the correct day regardless of timezone conversion
                 (
-                    start_utc.format("%Y-%m-%d").to_string(),
+                    self.start_date.format("%Y-%m-%d").to_string(),
                     start_utc.format("%H:%M").to_string(),
-                    end_utc.format("%Y-%m-%d").to_string(),
+                    self.end_date.format("%Y-%m-%d").to_string(),
                     end_utc.format("%H:%M").to_string(),
                 )
             } else {

frontend/src/components/week_view.rs

@@ -1229,15 +1229,12 @@ fn pixels_to_time(pixels: f64, time_increment: u32) -> NaiveTime {
 fn calculate_event_position(event: &VEvent, date: NaiveDate, time_increment: u32, print_pixels_per_hour: Option<f64>, print_start_hour: Option<u32>) -> (f32, f32, bool) {
     // Convert UTC times to local time for display
     let local_start = event.dtstart.with_timezone(&Local);
-    let event_date = local_start.date_naive();
     
-    // Position events based on when they appear in local time, not their original date
+    // Events should display based on their stored date (which now preserves the original local date)
-    // For timezone issues: an event created at 10 PM Sunday might be stored as Monday UTC
+    // not the calculated local date from UTC conversion, since we fixed the creation logic
-    // but should still display on Sunday's column since that's when the user sees it
+    let event_date = event.dtstart.date_naive(); // Use the stored date, not the converted local date
-    let should_display_here = event_date == date || 
-        (event_date == date - chrono::Duration::days(1) && local_start.hour() >= 20);
     
-    if !should_display_here {
+    if event_date != date {
         return (0.0, 0.0, false); // Event not on this date
     }