feat: Add task scheduling and reminders system

Add comprehensive scheduling functionality with reminder notifications:

- Add scheduledDate, scheduledTime, and reminderMinutes fields to ImmerseTask
- Add enableReminders and defaultReminderMinutes to plugin settings
- Implement reminder notification system with 30-second background checks
- Add overdue task detection with visual indicators
- Add native HTML5 date/time pickers in Quick Add and Edit modals
- Add reminder dropdown with 5/10/15/30/60 minute options
- Display scheduled date/time with blue badge (📅) in task list
- Show pulsing red "OVERDUE" badge (⚠️) for past-due tasks
- Add red left border highlight for overdue tasks
- Implement startup check for due/overdue tasks when plugin loads
- Show overdue notices when Obsidian opens if tasks are past due
- Play alert sounds for reminders (if sounds enabled)
- Track shown reminders to prevent duplicate notifications

src/view.ts

@@ -326,9 +326,13 @@ export class ImmerseView extends ItemView {
 
 	renderTaskItem(container: Element, task: ImmerseTask) {
 		const list = this.plugin.settings.lists.find(l => l.id === task.list);
-		
-		const taskEl = container.createEl('div', { 
-			cls: `immerse-task-item ${task.completed ? 'completed' : ''} ${task.isActive ? 'active' : ''}` 
+
+		// Check if task is overdue
+		const isOverdue = !task.completed && task.scheduledDate && task.scheduledTime &&
+			new Date(`${task.scheduledDate}T${task.scheduledTime}`).getTime() < Date.now();
+
+		const taskEl = container.createEl('div', {
+			cls: `immerse-task-item ${task.completed ? 'completed' : ''} ${task.isActive ? 'active' : ''} ${isOverdue ? 'overdue' : ''}`
 		});
 		
 		// Checkbox
@@ -363,7 +367,7 @@ export class ImmerseView extends ItemView {
 		
 		const taskMeta = content.createEl('div', { cls: 'immerse-task-meta' });
 		taskMeta.createEl('span', { text: `Est: ${this.plugin.formatTimeHuman(task.estimatedMinutes)}` });
-		
+
 		if (task.actualMinutes > 0) {
 			const actualSpan = taskMeta.createEl('span');
 			actualSpan.setText(`Actual: ${this.plugin.formatTimeHuman(task.actualMinutes)}`);
@@ -372,6 +376,23 @@ export class ImmerseView extends ItemView {
 			}
 		}
 
+		// Show scheduled date/time if set
+		if (task.scheduledDate) {
+			const scheduleSpan = taskMeta.createEl('span', {
+				cls: `immerse-schedule-badge ${isOverdue ? 'overdue' : ''}`
+			});
+			const dateStr = task.scheduledDate;
+			const timeStr = task.scheduledTime || '';
+			if (isOverdue) {
+				scheduleSpan.setText(`⚠️ OVERDUE: ${dateStr}${timeStr ? ' ' + timeStr : ''}`);
+			} else {
+				scheduleSpan.setText(`📅 ${dateStr}${timeStr ? ' ' + timeStr : ''}`);
+			}
+			if (task.reminderMinutes) {
+				scheduleSpan.title = `Reminder set for ${task.reminderMinutes} min before`;
+			}
+		}
+
 		// Actions
 		const actions = taskEl.createEl('div', { cls: 'immerse-task-actions' });