feat: Add Nextcloud WebDAV integration for cross-device synchronization

- Add NextcloudStorage class with WebDAV API support
- Add Settings tab with Nextcloud configuration
- Pre-configure with user's Nextcloud credentials (wralto.org/nextcloud3)
- Auto-test and enable Nextcloud sync on app startup
- Add data export/import functionality
- Add backup/restore capabilities
- Add clear data confirmation
- Add sync status indicator
- Add statistics overview in settings
- Fallback to localStorage if Nextcloud unavailable
- All existing features preserved (Bio checkbox, today period, recent entries)

Generated by Vibe Code

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

styles.css

@@ -815,3 +815,124 @@ header p {
 .organic-badge:hover {
     transform: scale(1.1);
 }
+
+/* Settings Section */
+.settings-section {
+    background-color: var(--card-bg);
+    border-radius: var(--border-radius);
+    padding: 20px;
+    box-shadow: var(--box-shadow);
+    margin-bottom: 20px;
+}
+
+.settings-section h3 {
+    margin-bottom: 15px;
+    color: var(--text-color);
+    border-bottom: 2px solid var(--primary-light);
+    padding-bottom: 10px;
+}
+
+.settings-section p {
+    color: var(--text-light);
+    margin-bottom: 20px;
+    line-height: 1.6;
+}
+
+/* Status Message */
+.status-message {
+    margin-top: 15px;
+    padding: 10px;
+    border-radius: var(--border-radius);
+    font-size: 0.9rem;
+}
+
+.status-message.success {
+    background-color: rgba(40, 167, 69, 0.1);
+    color: var(--success-color);
+    border: 1px solid var(--success-color);
+}
+
+.status-message.error {
+    background-color: rgba(220, 53, 69, 0.1);
+    color: var(--danger-color);
+    border: 1px solid var(--danger-color);
+}
+
+.status-message.info {
+    background-color: rgba(78, 205, 196, 0.1);
+    color: var(--secondary-color);
+    border: 1px solid var(--secondary-color);
+}
+
+/* Status Badge */
+.status-badge {
+    display: inline-block;
+    padding: 6px 12px;
+    border-radius: 20px;
+    font-size: 0.9rem;
+    font-weight: 600;
+}
+
+.status-badge.local {
+    background-color: #6c757d;
+    color: white;
+}
+
+.status-badge.connected {
+    background-color: var(--success-color);
+    color: white;
+}
+
+.status-badge.disconnected {
+    background-color: var(--danger-color);
+    color: white;
+}
+
+.status-badge.syncing {
+    background-color: var(--warning-color);
+    color: #333;
+}
+
+/* Stats Overview */
+.stats-overview {
+    display: grid;
+    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
+    gap: 15px;
+    margin-top: 15px;
+}
+
+.stat-item {
+    display: flex;
+    justify-content: space-between;
+    padding: 10px;
+    background-color: #f9f9f9;
+    border-radius: var(--border-radius);
+}
+
+.stat-label {
+    color: var(--text-light);
+    font-size: 0.9rem;
+}
+
+.stat-value {
+    color: var(--text-color);
+    font-weight: 600;
+}
+
+/* Modal for Import/Export */
+.modal-textarea {
+    width: 100%;
+    min-height: 200px;
+    font-family: monospace;
+    font-size: 0.85rem;
+    background-color: #f5f5f5;
+    border: 2px solid #ddd;
+    border-radius: var(--border-radius);
+    padding: 12px;
+    resize: vertical;
+}
+
+.modal-textarea:focus {
+    outline: none;
+    border-color: var(--primary-color);
+}