Add email reminders to calendar episodes; v1.1.15

- Per-episode reminder select (1d/2d/3d/1wk/2wk before publish date)
- Server checks hourly; fires Resend email to admin on reminder day
- reminderSentAt persisted so reminders don't re-fire; cleared if date or setting changes
- Bell indicator on calendar chips; sent confirmation in edit popover

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/App.css

@@ -10575,6 +10575,20 @@
 
 .cal-ep-chip-title { color: #4a8a58; }
 
+.cal-ep-bell {
+  font-size: 0.6rem;
+  margin-left: 2px;
+  opacity: 0.75;
+  vertical-align: middle;
+}
+
+.cal-reminder-sent {
+  font-size: 0.72rem;
+  color: #4ade80;
+  margin-top: 0.25rem;
+  display: block;
+}
+
 .cal-sidebar {
   width: 220px;
   flex-shrink: 0;