Coverage priorities 1-5: test pure functions, extract interfaces, mock-based handler tests

- Priority 1: Test NewSendEmailTask + NewSendPushTask (5 tests)
- Priority 2: Test customHTTPErrorHandler — all 15+ branches (21 tests)
- Priority 3: Extract Enqueuer interface + payload builders in worker pkg (5 tests)
- Priority 4: Extract ClassifyFile/ComputeRelPath in migrate-encrypt (6 tests)
- Priority 5: Define Handler interfaces, refactor to accept them, mock-based tests (14 tests)
- Fix .gitignore: /worker instead of worker to stop ignoring internal/worker/

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

internal/worker/jobs/handler_helpers.go

@@ -0,0 +1,39 @@
+package jobs
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/treytartt/honeydue-api/internal/models"
+)
+
+// BuildDigestMessage constructs the daily digest notification text.
+func BuildDigestMessage(overdueCount, dueThisWeekCount int) (title, body string) {
+	title = "Daily Task Summary"
+	if overdueCount > 0 && dueThisWeekCount > 0 {
+		body = fmt.Sprintf("You have %d overdue task(s) and %d task(s) due this week", overdueCount, dueThisWeekCount)
+	} else if overdueCount > 0 {
+		body = fmt.Sprintf("You have %d overdue task(s) that need attention", overdueCount)
+	} else {
+		body = fmt.Sprintf("You have %d task(s) due this week", dueThisWeekCount)
+	}
+	return
+}
+
+// IsOverdueStage checks if a reminder stage string represents overdue.
+func IsOverdueStage(stage string) bool {
+	return strings.HasPrefix(stage, "overdue")
+}
+
+// ExtractFrequencyDays gets interval days from a task's frequency.
+func ExtractFrequencyDays(t *models.Task) *int {
+	if t.Frequency != nil && t.Frequency.Days != nil {
+		days := *t.Frequency.Days
+		return &days
+	}
+	if t.CustomIntervalDays != nil {
+		days := *t.CustomIntervalDays
+		return &days
+	}
+	return nil
+}