feat: add Dashboard with latest card and weight chart

src/screens/DashboardScreen.tsx

@@ -0,0 +1,44 @@
+import React, { useCallback, useState } from 'react'
+import { View, ScrollView, TouchableOpacity, Text, StyleSheet } from 'react-native'
+import { useFocusEffect } from '@react-navigation/native'
+import { initDatabase, getAllMeasurements, getLatestMeasurement } from '../database/db'
+import { Measurement } from '../types'
+import LatestMeasurementCard from '../components/LatestMeasurementCard'
+import WeightChart from '../components/WeightChart'
+
+type Props = { navigation: any }
+
+export default function DashboardScreen({ navigation }: Props) {
+  const [latest, setLatest] = useState<Measurement | null>(null)
+  const [all, setAll] = useState<Measurement[]>([])
+
+  useFocusEffect(
+    useCallback(() => {
+      const load = async () => {
+        await initDatabase()
+        const allM = await getAllMeasurements()
+        setAll(allM)
+        const latestM = await getLatestMeasurement()
+        setLatest(latestM)
+      }
+      load()
+    }, [])
+  )
+
+  return (
+    <ScrollView style={styles.container}>
+      <LatestMeasurementCard measurement={latest} />
+      <WeightChart measurements={all} />
+
+      <TouchableOpacity style={styles.fab} onPress={() => navigation.navigate('NewMeasurement')}>
+        <Text style={styles.fabText}>+ Nieuwe meting</Text>
+      </TouchableOpacity>
+    </ScrollView>
+  )
+}
+
+const styles = StyleSheet.create({
+  container: { flex: 1, backgroundColor: '#f5f5f5' },
+  fab: { backgroundColor: '#4CAF50', padding: 16, borderRadius: 8, margin: 16, alignItems: 'center' },
+  fabText: { color: '#fff', fontSize: 16, fontWeight: '700' },
+})