refactor: split sqlite.go and server.go by domain (FLAW-20)

Pure moves, no behaviour change: the storage layer now has users,
apikeys, thoughts, tasklists, documents, folders, tags, lists, teams and
system files next to sqlite.go (store, schema, migrations); the API has
handlers_*.go per area plus realtime.go and alarms.go next to server.go
(server, router, middleware). Declarations were moved verbatim with an
AST-based tool; imports pruned with goimports.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/api/alarms.go

@@ -0,0 +1,157 @@
+package api
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"log/slog"
+	"time"
+
+	"github.com/sandrodach/mindsift/internal/domain"
+)
+
+// --- MULTI-CHANNEL ALARM DISPATCHER (EMAIL, DISCORD, CUSTOM WEBHOOK) ---
+
+func (s *Server) sendEmailNotification(toEmail, subject, bodyText string) error {
+	cfg, err := s.smtpSettings()
+	if err != nil {
+		return err
+	}
+	if err := sendMail(cfg, toEmail, subject, bodyText); err != nil {
+		step := ""
+		if se, ok := err.(*smtpStepError); ok {
+			step = se.Step
+		}
+		slog.Warn("E-Mail-Versand fehlgeschlagen", "smtp_step", step, "host", cfg.Host, "port", cfg.Port, "to", toEmail, "error", err)
+		return err
+	}
+	return nil
+}
+
+func (s *Server) sendDiscordNotification(webhookURL, title, description, dueDate, priority string) error {
+	allowPrivate := s.allowPrivateWebhooks()
+	if err := validateWebhookURL(webhookURL, true, allowPrivate); err != nil {
+		return err
+	}
+	httpClient := guardedClient(allowPrivate)
+	payload := map[string]interface{}{
+		"content": "⏰ **MindSift Aufgaben-Alarm**",
+		"embeds": []map[string]interface{}{
+			{
+				"title":       title,
+				"description": fmt.Sprintf("%s\n\n**Fällig:** %s | **Priorität:** %s", description, dueDate, priority),
+				"color":       2450411,
+				"footer": map[string]string{
+					"text": "MindSift Alarm-System",
+				},
+			},
+		},
+	}
+	body, err := json.Marshal(payload)
+	if err != nil {
+		return err
+	}
+	resp, err := httpClient.Post(webhookURL, "application/json", bytes.NewReader(body))
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode >= 400 {
+		return fmt.Errorf("HTTP Status %d", resp.StatusCode)
+	}
+	return nil
+}
+
+func (s *Server) sendCustomWebhookNotification(webhookURL, event, title, notes, dueDate, priority string) error {
+	allowPrivate := s.allowPrivateWebhooks()
+	if err := validateWebhookURL(webhookURL, false, allowPrivate); err != nil {
+		return err
+	}
+	httpClient := guardedClient(allowPrivate)
+	payload := map[string]interface{}{
+		"event":     event,
+		"title":     title,
+		"notes":     notes,
+		"dueDate":   dueDate,
+		"priority":  priority,
+		"timestamp": domain.NowISO(),
+	}
+	body, err := json.Marshal(payload)
+	if err != nil {
+		return err
+	}
+	resp, err := httpClient.Post(webhookURL, "application/json", bytes.NewReader(body))
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode >= 400 {
+		return fmt.Errorf("HTTP Status %d", resp.StatusCode)
+	}
+	return nil
+}
+
+// alarmDue reports whether the alarm for a due date should go out now: from the due time (09:00 for
+// all-day tasks) minus the user's lead time on. Unreadable dates never fire.
+func alarmDue(dueDate string, notifyBeforeMinutes int, now time.Time) bool {
+	at, ok := domain.DueAlarmAt(dueDate, notifyBeforeMinutes, now.Location())
+	return ok && !now.Before(at)
+}
+
+func (s *Server) startAlarmTicker() {
+	ticker := time.NewTicker(60 * time.Second)
+	defer ticker.Stop()
+
+	for range ticker.C {
+		alarms, err := s.store.GetDueTasksForAlarm()
+		if err != nil || len(alarms) == 0 {
+			continue
+		}
+
+		now := time.Now()
+
+		for _, a := range alarms {
+			if !alarmDue(a.DueDate, a.NotifyBeforeMinutes, now) {
+				continue
+			}
+			if len(a.AlarmChannels) == 0 {
+				continue
+			}
+
+			sentAny := false
+			due := domain.HumanDue(a.DueDate)
+			desc := a.Notes
+			if desc == "" {
+				desc = "Aufgabe ist jetzt fällig."
+			}
+
+			for _, ch := range a.AlarmChannels {
+				switch ch {
+				case "discord":
+					if a.DiscordWebhookURL != "" {
+						if err := s.sendDiscordNotification(a.DiscordWebhookURL, a.Title, desc, due, a.Priority); err == nil {
+							sentAny = true
+						}
+					}
+				case "webhook":
+					if a.CustomWebhookURL != "" {
+						if err := s.sendCustomWebhookNotification(a.CustomWebhookURL, "task_due", a.Title, desc, a.DueDate, a.Priority); err == nil {
+							sentAny = true
+						}
+					}
+				case "email":
+					if a.AlarmEmail != "" {
+						emailBody := fmt.Sprintf("Hallo,\n\ndeine Aufgabe in MindSift ist fällig:\n\nAufgabe: %s\nFällig am: %s\nPriorität: %s\nNotizen: %s\n", a.Title, due, a.Priority, desc)
+						if err := s.sendEmailNotification(a.AlarmEmail, "⏰ Aufgabe fällig: "+a.Title, emailBody); err == nil {
+							sentAny = true
+						}
+					}
+				}
+			}
+
+			if sentAny {
+				_ = s.store.MarkTaskAlarmSent(a.TaskID)
+			}
+		}
+	}
+}