feat: add PersonNameParser utility for ODS name normalisation

Pure static utility that parses raw name strings from the ODS into
structured Person data. Handles multi-receiver patterns like
"Walter und Eugenie de Gruyter" → [Walter de Gruyter, Eugenie de Gruyter],
parenthesised last names, "geb." maiden-name stripping, and
"Familie" filtering. Includes unit tests for all patterns found in the data.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/src/test/java/org/raddatz/familienarchiv/service/PersonNameParserTest.java

@@ -0,0 +1,120 @@
+package org.raddatz.familienarchiv.service;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class PersonNameParserTest {
+
+    // --- parseReceivers ---
+
+    @Test
+    void singlePerson_noChange() {
+        assertThat(PersonNameParser.parseReceivers("Walter de Gruyter"))
+                .containsExactly("Walter de Gruyter");
+    }
+
+    @Test
+    void gebAnnotation_stripped() {
+        assertThat(PersonNameParser.parseReceivers("Eugenie de Gruyter geb. Müller"))
+                .containsExactly("Eugenie de Gruyter");
+    }
+
+    @Test
+    void twoFirstNames_sharedKnownLastName_und() {
+        assertThat(PersonNameParser.parseReceivers("Walter und Eugenie de Gruyter"))
+                .containsExactly("Walter de Gruyter", "Eugenie de Gruyter");
+    }
+
+    @Test
+    void twoFirstNames_sharedKnownLastName_u() {
+        assertThat(PersonNameParser.parseReceivers("Herbert und Clara Cram"))
+                .containsExactly("Herbert Cram", "Clara Cram");
+    }
+
+    @Test
+    void twoFirstNames_sharedKnownLastName_u_short() {
+        assertThat(PersonNameParser.parseReceivers("Ella u Walter Dieckmann"))
+                .containsExactly("Ella Dieckmann", "Walter Dieckmann");
+    }
+
+    @Test
+    void twoFirstNames_parenthesisedLastName() {
+        assertThat(PersonNameParser.parseReceivers("Hedi und Tutu (Gruber)"))
+                .containsExactly("Hedi Gruber", "Tutu Gruber");
+    }
+
+    @Test
+    void twoPersons_differentLastNames() {
+        assertThat(PersonNameParser.parseReceivers("Clara Cram u Ellen B-M"))
+                .containsExactly("Clara Cram", "Ellen B-M");
+    }
+
+    @Test
+    void familie_filtered_out() {
+        assertThat(PersonNameParser.parseReceivers("Clara u Familie"))
+                .containsExactly("Clara");
+    }
+
+    @Test
+    void twoFirstNames_noLastName() {
+        assertThat(PersonNameParser.parseReceivers("Walter und Eugenie"))
+                .containsExactly("Walter", "Eugenie");
+    }
+
+    @Test
+    void nullInput_returnsEmpty() {
+        assertThat(PersonNameParser.parseReceivers(null)).isEmpty();
+    }
+
+    @Test
+    void blankInput_returnsEmpty() {
+        assertThat(PersonNameParser.parseReceivers("   ")).isEmpty();
+    }
+
+    // --- split ---
+
+    @Test
+    void split_knownMultiWordLastName() {
+        PersonNameParser.SplitName result = PersonNameParser.split("Walter de Gruyter");
+        assertThat(result.firstName()).isEqualTo("Walter");
+        assertThat(result.lastName()).isEqualTo("de Gruyter");
+    }
+
+    @Test
+    void split_knownSingleWordLastName() {
+        PersonNameParser.SplitName result = PersonNameParser.split("Clara Cram");
+        assertThat(result.firstName()).isEqualTo("Clara");
+        assertThat(result.lastName()).isEqualTo("Cram");
+    }
+
+    @Test
+    void split_unknownLastName_fallsBackToLastSpace() {
+        PersonNameParser.SplitName result = PersonNameParser.split("Ellen Burkhard-Meier");
+        assertThat(result.firstName()).isEqualTo("Ellen");
+        assertThat(result.lastName()).isEqualTo("Burkhard-Meier");
+    }
+
+    @Test
+    void split_singleToken_lastNameIsPlaceholder() {
+        PersonNameParser.SplitName result = PersonNameParser.split("Clara");
+        assertThat(result.firstName()).isEqualTo("Clara");
+        assertThat(result.lastName()).isEqualTo("?");
+    }
+
+    @Test
+    void split_gebAnnotation_stripped() {
+        PersonNameParser.SplitName result = PersonNameParser.split("Eugenie de Gruyter geb. Müller");
+        assertThat(result.firstName()).isEqualTo("Eugenie");
+        assertThat(result.lastName()).isEqualTo("de Gruyter");
+    }
+
+    @Test
+    void split_null_returnsPlaceholder() {
+        PersonNameParser.SplitName result = PersonNameParser.split(null);
+        assertThat(result.firstName()).isEqualTo("?");
+        assertThat(result.lastName()).isEqualTo("?");
+    }
+}