Fix: Lade Nextcloud-Daten vor dem Speichern, um Datenverlust zu vermeiden

- Aendert loadData(): Laedt zuerst Nextcloud-Daten und faellt nur bei fehlenden
  Dateien auf localStorage zurueck
- Aendert saveNextcloudConfig(): Laedt Daten von Nextcloud BEVOR sie gespeichert
  werden, um Ueberschreiben bestehender Nextcloud-Daten zu verhindern
- Behebt das Problem, dass lokale Daten die Nextcloud-Daten ueberschreiben

Fixes: Datenverlust bei Nextcloud-Anmeldung

Co-authored-by: trevor1969 <trevor1969@users.noreply.github.com>

app.js

@@ -280,6 +280,7 @@ class TeeTracker {
             const teas = await this.nextcloudStorage.loadFile(DATA_DIRECTORY + 'teas.json');
             const entries = await this.nextcloudStorage.loadFile(DATA_DIRECTORY + 'entries.json');
             
+            // Load from Nextcloud if available
             if (teas) {
                 this.teas = teas.map(tea => ({
                     ...tea,
@@ -295,9 +296,38 @@ class TeeTracker {
                 }));
             }
             
-            // If Nextcloud loading failed, fall back to localStorage
+            // If any data is missing from Nextcloud, load from localStorage
-            if (!teas || !entries) {
+            // This prevents data loss when switching to Nextcloud
+            if (!teas && !entries) {
+                // Both Nextcloud files are missing, load everything from localStorage
                 this.loadFromLocalStorage();
+            } else if (!teas) {
+                // Only teas.json is missing from Nextcloud, load teas from localStorage
+                const localTeas = localStorage.getItem(STORAGE_KEY_TEAS);
+                if (localTeas) {
+                    try {
+                        this.teas = JSON.parse(localTeas).map(tea => ({
+                            ...tea,
+                            organic: tea.organic !== undefined ? tea.organic : false,
+                            rating: tea.rating !== undefined ? tea.rating : 3
+                        }));
+                    } catch (error) {
+                        console.error('Error loading local teas:', error);
+                    }
+                }
+            } else if (!entries) {
+                // Only entries.json is missing from Nextcloud, load entries from localStorage
+                const localEntries = localStorage.getItem(STORAGE_KEY_ENTRIES);
+                if (localEntries) {
+                    try {
+                        this.entries = JSON.parse(localEntries).map(entry => ({
+                            ...entry,
+                            teaspoons: entry.teaspoons !== undefined ? entry.teaspoons : 1
+                        }));
+                    } catch (error) {
+                        console.error('Error loading local entries:', error);
+                    }
+                }
             }
         } else {
             // Load from localStorage
@@ -949,30 +979,6 @@ class TeeTracker {
                     return;
                 }
                 
-                // Load existing data from localStorage before switching to Nextcloud
-                // This prevents data loss when connecting to Nextcloud for the first time
-                const existingTeas = localStorage.getItem(STORAGE_KEY_TEAS);
-                const existingEntries = localStorage.getItem(STORAGE_KEY_ENTRIES);
-                
-                if (existingTeas) {
-                    try {
-                        this.teas = JSON.parse(existingTeas).map(tea => ({
-                            ...tea,
-                            organic: tea.organic !== undefined ? tea.organic : false
-                        }));
-                    } catch (error) {
-                        console.error('Error loading existing teas:', error);
-                    }
-                }
-                
-                if (existingEntries) {
-                    try {
-                        this.entries = JSON.parse(existingEntries);
-                    } catch (error) {
-                        console.error('Error loading existing entries:', error);
-                    }
-                }
-                
                 // Save config WITHOUT password for security
                 // Password will be requested each time or stored in sessionStorage
                 const config = { baseUrl: url, username, path };
@@ -985,7 +991,11 @@ class TeeTracker {
                 this.nextcloudStorage = ncStorage;
                 this.useNextcloud = true;
                 
-                // Save current data to Nextcloud
+                // Load data from Nextcloud first (this is the critical fix!)
+                // This will automatically fall back to localStorage if Nextcloud has no data
+                await this.loadData();
+                
+                // Save the loaded/merged data to Nextcloud
                 await this.saveData();
                 
                 this.showStatusMessage('✅ Konfiguration gespeichert und Daten synchronisiert!', 'success');