refactor: address PR review concerns

- Remove Architekt from WORD_PREFIXES (classifier handles it)
- Use Objects.equals for null-safe firstName/lastName comparison
- Remove unused trimmed variable in PersonTypeClassifier
- Fix containsWord to loop through all occurrences (finds
  "Eltern" in "Nachbareltern Eltern")
- Extract DisplayNameFormatter utility shared by Person and
  PersonSummaryDTO to eliminate display logic duplication

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

backend/src/main/java/org/raddatz/familienarchiv/dto/PersonSummaryDTO.java

@@ -20,10 +20,7 @@ public interface PersonSummaryDTO {
     long getDocumentCount();
 
     default String getDisplayName() {
-        StringBuilder sb = new StringBuilder();
-        if (getTitle() != null) sb.append(getTitle()).append(" ");
-        if (getFirstName() != null) sb.append(getFirstName()).append(" ");
-        sb.append(getLastName());
-        return sb.toString().trim();
+        return org.raddatz.familienarchiv.model.DisplayNameFormatter.format(
+                getTitle(), getFirstName(), getLastName());
     }
 }

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

@@ -0,0 +1,12 @@
+package org.raddatz.familienarchiv.model;
+
+public class DisplayNameFormatter {
+
+    public static String format(String title, String firstName, String lastName) {
+        StringBuilder sb = new StringBuilder();
+        if (title != null) sb.append(title).append(" ");
+        if (firstName != null) sb.append(firstName).append(" ");
+        sb.append(lastName);
+        return sb.toString().trim();
+    }
+}

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

@@ -58,10 +58,6 @@ public class Person {
     @Transient
     @Schema(accessMode = Schema.AccessMode.READ_ONLY, requiredMode = Schema.RequiredMode.REQUIRED)
     public String getDisplayName() {
-        StringBuilder sb = new StringBuilder();
-        if (title != null) sb.append(title).append(" ");
-        if (firstName != null) sb.append(firstName).append(" ");
-        sb.append(lastName);
-        return sb.toString().trim();
+        return DisplayNameFormatter.format(title, firstName, lastName);
     }
 }

backend/src/main/java/org/raddatz/familienarchiv/service/PersonNameParser.java

@@ -3,6 +3,7 @@ package org.raddatz.familienarchiv.service;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
+import java.util.Objects;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -159,7 +160,7 @@ public class PersonNameParser {
             if ("?".equals(lastName) && !cleaned.contains(" ")) {
                 lastName = firstName;
                 firstName = null;
-            } else if (firstName.equals(lastName)) {
+            } else if (Objects.equals(firstName, lastName)) {
                 firstName = null;
             }
         }
@@ -217,7 +218,7 @@ public class PersonNameParser {
             "Frau", "Herr", "Freifrau", "Freiherr",
             "Tante", "Onkel", "Schwester", "Bruder",
             "Cousine", "Cousin", "Freundin", "Freund",
-            "Mutter", "Vater", "Pastor", "Architekt");
+            "Mutter", "Vater", "Pastor");
 
     /** Strips known title/relationship prefixes, looping for stacked titles. */
     public static TitleResult stripTitle(String input) {

backend/src/main/java/org/raddatz/familienarchiv/service/PersonTypeClassifier.java

@@ -24,8 +24,7 @@ public class PersonTypeClassifier {
     public static PersonType classify(String rawName) {
         if (rawName == null || rawName.isBlank()) return PersonType.PERSON;
 
-        String trimmed = rawName.trim();
-        String lower = trimmed.toLowerCase();
+        String lower = rawName.trim().toLowerCase();
 
         for (String keyword : SKIP_KEYWORDS) {
             if (lower.startsWith(keyword.toLowerCase())) return PersonType.SKIP;
@@ -50,11 +49,15 @@ public class PersonTypeClassifier {
     }
 
     private static boolean containsWord(String text, String word) {
-        int idx = text.indexOf(word);
-        if (idx < 0) return false;
-        boolean startOk = idx == 0 || !Character.isLetter(text.charAt(idx - 1));
-        int end = idx + word.length();
-        boolean endOk = end >= text.length() || !Character.isLetter(text.charAt(end));
-        return startOk && endOk;
+        int fromIndex = 0;
+        while (true) {
+            int idx = text.indexOf(word, fromIndex);
+            if (idx < 0) return false;
+            boolean startOk = idx == 0 || !Character.isLetter(text.charAt(idx - 1));
+            int end = idx + word.length();
+            boolean endOk = end >= text.length() || !Character.isLetter(text.charAt(end));
+            if (startOk && endOk) return true;
+            fromIndex = idx + 1;
+        }
     }
 }

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

@@ -86,4 +86,9 @@ class PersonTypeClassifierTest {
     void classify_caseInsensitive() {
         assertThat(PersonTypeClassifier.classify("firma auschrath")).isEqualTo(PersonType.INSTITUTION);
     }
+
+    @Test
+    void classify_containsWord_findsSecondOccurrence() {
+        assertThat(PersonTypeClassifier.classify("Nachbareltern Eltern")).isEqualTo(PersonType.GROUP);
+    }
 }