Make reminder schedules additive across frequency tiers

Each frequency tier now inherits all reminder days from smaller tiers:
- Monthly: 3d, 1d, day-of (was: 3d, day-of)
- Quarterly: 7d, 3d, 1d, day-of (was: 7d, 3d, day-of)
- Semi-Annual: 14d, 7d, 3d, 1d, day-of (was: 14d, 7d, day-of)
- Annual: 30d, 14d, 7d, 3d, 1d, day-of (was: 30d, 14d, 7d, day-of)

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/notifications/reminder_config.go

@@ -20,17 +20,17 @@ var OverdueConfig = struct {
 // Key: interval days (matches TaskFrequency.days in DB, 0 = Once/null)
 // Value: array of days before due date to send reminders (0 = day-of)
 //
-// To add a reminder: append the number of days before to the slice
-// Example: FrequencySchedules[30] = []int{7, 3, 0} adds 7-day warning to Monthly
+// Schedules are ADDITIVE - each tier inherits all reminders from smaller tiers
+// Example: Monthly (30) gets 3d + 1d + day-of because it includes Bi-Weekly's 1d
 var FrequencySchedules = map[int][]int{
-	0:   {0},             // 1. Once (null/0): day-of only
-	1:   {0},             // 2. Daily: day-of only
-	7:   {0},             // 3. Weekly: day-of only
-	14:  {1, 0},          // 4. Bi-Weekly: 1 day before, day-of
-	30:  {3, 0},          // 5. Monthly: 3 days before, day-of
-	90:  {7, 3, 0},       // 6. Quarterly: 7d, 3d, day-of
-	180: {14, 7, 0},      // 7. Semi-Annually: 14d, 7d, day-of
-	365: {30, 14, 7, 0},  // 8. Annually: 30d, 14d, 7d, day-of
+	0:   {0},                      // 1. Once (null/0): day-of only
+	1:   {0},                      // 2. Daily: day-of only
+	7:   {0},                      // 3. Weekly: day-of only
+	14:  {1, 0},                   // 4. Bi-Weekly: 1d, day-of
+	30:  {3, 1, 0},                // 5. Monthly: 3d, 1d, day-of
+	90:  {7, 3, 1, 0},             // 6. Quarterly: 7d, 3d, 1d, day-of
+	180: {14, 7, 3, 1, 0},         // 7. Semi-Annually: 14d, 7d, 3d, 1d, day-of
+	365: {30, 14, 7, 3, 1, 0},     // 8. Annually: 30d, 14d, 7d, 3d, 1d, day-of
 }
 
 // HumanReadableSchedule returns admin-friendly description for each frequency
@@ -40,11 +40,11 @@ var HumanReadableSchedule = map[int]string{
 	0:   "Day-of → Overdue (tapering)",
 	1:   "Day-of → Overdue (tapering)",
 	7:   "Day-of → Overdue (tapering)",
-	14:  "1 day before → Day-of → Overdue",
-	30:  "3 days before → Day-of → Overdue",
-	90:  "7d → 3d → Day-of → Overdue",
-	180: "14d → 7d → Day-of → Overdue",
-	365: "30d → 14d → 7d → Day-of → Overdue",
+	14:  "1d → Day-of → Overdue",
+	30:  "3d → 1d → Day-of → Overdue",
+	90:  "7d → 3d → 1d → Day-of → Overdue",
+	180: "14d → 7d → 3d → 1d → Day-of → Overdue",
+	365: "30d → 14d → 7d → 3d → 1d → Day-of → Overdue",
 }
 
 // FrequencyNames maps interval days to frequency names for display