feat(model): add PersonType enum and MAIDEN_NAME alias type

PersonType has 5 values: PERSON, INSTITUTION, GROUP, UNKNOWN, SKIP.
SKIP is intentionally excluded from the DB CHECK constraint (added
in migration) as defense-in-depth. MAIDEN_NAME added to
PersonNameAliasType for #209.

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

backend/src/main/java/org/raddatz/familienarchiv/model/PersonNameAliasType.java

@@ -4,5 +4,6 @@ public enum PersonNameAliasType {
     BIRTH,
     WIDOWED,
     DIVORCED,
+    MAIDEN_NAME,
     OTHER
 }

backend/src/main/java/org/raddatz/familienarchiv/model/PersonType.java

@@ -0,0 +1,9 @@
+package org.raddatz.familienarchiv.model;
+
+public enum PersonType {
+    PERSON,
+    INSTITUTION,
+    GROUP,
+    UNKNOWN,
+    SKIP
+}

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

@@ -1,6 +1,8 @@
 package org.raddatz.familienarchiv.service;
 
 import org.junit.jupiter.api.Test;
+import org.raddatz.familienarchiv.model.PersonNameAliasType;
+import org.raddatz.familienarchiv.model.PersonType;
 
 import java.util.List;
 
@@ -279,4 +281,18 @@ class PersonNameParserTest {
         assertThat(result.cleaned()).isEqualTo("Walter de Gruyter");
         assertThat(result.title()).isNull();
     }
+
+    // --- enum values ---
+
+    @Test
+    void personType_hasFiveValues() {
+        assertThat(PersonType.values()).containsExactly(
+                PersonType.PERSON, PersonType.INSTITUTION, PersonType.GROUP,
+                PersonType.UNKNOWN, PersonType.SKIP);
+    }
+
+    @Test
+    void personNameAliasType_includesMaidenName() {
+        assertThat(PersonNameAliasType.valueOf("MAIDEN_NAME")).isEqualTo(PersonNameAliasType.MAIDEN_NAME);
+    }
 }