feat(meals): customizable meal type visibility in Settings (#14)

Users can now toggle which meal types (breakfast, lunch, dinner, snack)
are displayed in the meal planner via a new Settings section. Preference
is stored household-wide in sync_config and applied as a filter on the
meals page. Includes preferences API, i18n (DE/EN/IT), and Settings UI.

server/routes/preferences.js

@@ -0,0 +1,91 @@
+/**
+ * Modul: Haushalt-Einstellungen (Preferences)
+ * Zweck: REST-API fuer haushaltweite Praeferenzen (via sync_config-Tabelle)
+ * Abhängigkeiten: express, server/db.js
+ */
+
+import { createLogger } from '../logger.js';
+import express from 'express';
+import * as db from '../db.js';
+
+const log = createLogger('Preferences');
+
+const router = express.Router();
+
+const VALID_MEAL_TYPES = ['breakfast', 'lunch', 'dinner', 'snack'];
+const DEFAULT_MEAL_TYPES = VALID_MEAL_TYPES.join(',');
+
+// --------------------------------------------------------
+// Hilfsfunktionen
+// --------------------------------------------------------
+
+function cfgGet(key) {
+  const row = db.get().prepare('SELECT value FROM sync_config WHERE key = ?').get(key);
+  return row ? row.value : null;
+}
+
+function cfgSet(key, value) {
+  db.get().prepare(`
+    INSERT INTO sync_config (key, value)
+    VALUES (?, ?)
+    ON CONFLICT(key) DO UPDATE SET value = excluded.value,
+                                   updated_at = strftime('%Y-%m-%dT%H:%M:%SZ', 'now')
+  `).run(key, value);
+}
+
+// --------------------------------------------------------
+// GET /api/v1/preferences
+// Alle Haushalt-Praeferenzen lesen.
+// Response: { data: { visible_meal_types: string[] } }
+// --------------------------------------------------------
+
+router.get('/', (req, res) => {
+  try {
+    const raw = cfgGet('visible_meal_types') ?? DEFAULT_MEAL_TYPES;
+    const visibleMealTypes = raw.split(',').filter((t) => VALID_MEAL_TYPES.includes(t));
+
+    res.json({
+      data: {
+        visible_meal_types: visibleMealTypes,
+      },
+    });
+  } catch (err) {
+    log.error('GET /', err);
+    res.status(500).json({ error: 'Interner Fehler', code: 500 });
+  }
+});
+
+// --------------------------------------------------------
+// PUT /api/v1/preferences
+// Haushalt-Praeferenzen aktualisieren.
+// Body: { visible_meal_types: string[] }
+// Response: { data: { visible_meal_types: string[] } }
+// --------------------------------------------------------
+
+router.put('/', (req, res) => {
+  try {
+    const { visible_meal_types } = req.body;
+
+    if (!Array.isArray(visible_meal_types)) {
+      return res.status(400).json({ error: 'visible_meal_types muss ein Array sein', code: 400 });
+    }
+
+    const filtered = visible_meal_types.filter((t) => VALID_MEAL_TYPES.includes(t));
+    if (filtered.length === 0) {
+      return res.status(400).json({ error: 'Mindestens ein Mahlzeit-Typ muss aktiv sein', code: 400 });
+    }
+
+    cfgSet('visible_meal_types', filtered.join(','));
+
+    res.json({
+      data: {
+        visible_meal_types: filtered,
+      },
+    });
+  } catch (err) {
+    log.error('PUT /', err);
+    res.status(500).json({ error: 'Interner Fehler', code: 500 });
+  }
+});
+
+export default router;