Ok it might work

apk/app/add.tsx

@@ -0,0 +1,173 @@
+import DateTimePicker, {
+  DateTimePickerEvent,
+} from "@react-native-community/datetimepicker";
+import { useBirthdays } from "@/context/birthdays-context";
+import { useRouter } from "expo-router";
+import React, { useState } from "react";
+import {
+    Alert,
+    KeyboardAvoidingView,
+    Platform,
+    ScrollView,
+    StyleSheet,
+    Text,
+    TextInput,
+    TouchableOpacity,
+    View,
+} from "react-native";
+import { SafeAreaView } from "react-native-safe-area-context";
+
+export default function SimpleForm() {
+  const router = useRouter();
+  const { addBirthday } = useBirthdays();
+  const [name, setName] = useState("");
+  const [date, setDate] = useState(new Date());
+  const [showPicker, setShowPicker] = useState(false);
+
+  const onChangeDate = (
+    event: DateTimePickerEvent,
+    selectedDate?: Date
+  ) => {
+    setShowPicker(Platform.OS === "ios");
+    if (selectedDate) {
+      setDate(selectedDate);
+    }
+  };
+
+  const handleSubmit = () => {
+    if (!name.trim()) {
+      Alert.alert("Missing name", "Enter a name before saving.");
+      return;
+    }
+
+    addBirthday({
+      name,
+      date: formatBirthdayDate(date),
+    });
+    setName("");
+    setDate(new Date());
+    router.back();
+  };
+
+  return (
+    <SafeAreaView style={styles.safeArea} edges={["top", "bottom"]}>
+      <KeyboardAvoidingView
+        style={styles.keyboardContainer}
+        behavior={Platform.OS === "ios" ? "padding" : undefined}
+      >
+        <View style={styles.content}>
+          <Text style={styles.title}>Add Birthday</Text>
+          <ScrollView
+            contentContainerStyle={styles.scrollContent}
+            keyboardShouldPersistTaps="handled"
+          >
+            <View style={styles.formCard}>
+              <Text style={styles.label}>Name:</Text>
+              <TextInput
+                style={styles.input}
+                placeholder="Enter name of the person"
+                value={name}
+                onChangeText={setName}
+              />
+
+              <Text style={styles.label}>Date:</Text>
+              <TouchableOpacity
+                onPress={() => {
+                  setShowPicker(true);
+                }}
+                style={[{ backgroundColor: "#00adaa" }, styles.button]}
+              >
+                <Text style={styles.buttonText}>Select Date</Text>
+              </TouchableOpacity>
+
+              <Text style={styles.dateText}>
+                {"Selected date: " + date.toDateString()}
+              </Text>
+
+              {showPicker && (
+                <DateTimePicker
+                  value={date}
+                  mode="date"
+                  display="default"
+                  onChange={onChangeDate}
+                />
+              )}
+
+              <TouchableOpacity
+                onPress={handleSubmit}
+                style={[{ backgroundColor: "#00984c" }, styles.button]}
+              >
+                <Text style={styles.buttonText}>Save</Text>
+              </TouchableOpacity>
+            </View>
+          </ScrollView>
+        </View>
+      </KeyboardAvoidingView>
+    </SafeAreaView>
+  );
+}
+
+const styles = StyleSheet.create({
+  safeArea: {
+    flex: 1,
+    backgroundColor: "#fff",
+    justifyContent: "center",
+    marginBottom: 0,
+  },
+  keyboardContainer: {
+    flex: 1,
+  },
+  content: {
+    flex: 1,
+    paddingHorizontal: 16,
+    paddingTop: 12,
+  },
+  title: {
+    fontSize: 24,
+    fontWeight: "bold",
+    paddingHorizontal: 5,
+    paddingBottom: 10,
+  },
+  scrollContent: {
+    flexGrow: 1,
+    paddingHorizontal: 20,
+    paddingBottom: 20,
+  },
+  formCard: {
+    gap: 12,
+  },
+  label: {
+    paddingTop: 20,
+    fontSize: 16,
+  },
+  input: {
+    borderWidth: 1,
+    borderColor: "#ccc",
+    padding: 10,
+    borderRadius: 5,
+  },
+  dateText: {
+    fontSize: 16,
+    marginBottom: 8,
+  },
+  button: {
+    borderRadius: 10,
+    paddingVertical: 10,
+    paddingHorizontal: 12,
+    elevation: 8
+  },
+  buttonText: {
+    fontSize: 18,
+    color: "#fff",
+    fontWeight: "bold",
+    alignSelf: "center"
+  }
+});
+
+function formatBirthdayDate(date: Date) {
+  const year = date.getFullYear();
+  const month = `${date.getMonth() + 1}`.padStart(2, "0");
+  const day = `${date.getDate()}`.padStart(2, "0");
+
+  return `${year}-${month}-${day}`;
+}