feat(service): add PersonTypeClassifier with keyword heuristics

Static classify() method uses position-aware keyword matching:
- SKIP: Briefumschlag, Kondolenzbriefe, Hochzeitsgedicht (start)
- INSTITUTION: Firma, Architekt (start), GmbH, Co (end)
- GROUP: Familie, Comité, Comite, Geschwister, Gesellschafter,
  Garde, Mitarbeiter (start), Eltern, Kinder,
  Schwiegereltern (word boundary)
- PERSON: default for all other inputs

Case-insensitive. 25 parameterized test cases.

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

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

@@ -0,0 +1,60 @@
+package org.raddatz.familienarchiv.service;
+
+import java.util.List;
+import org.raddatz.familienarchiv.model.PersonType;
+
+public class PersonTypeClassifier {
+
+    private static final List<String> SKIP_KEYWORDS = List.of(
+            "Briefumschlag", "Kondolenzbriefe", "Hochzeitsgedicht");
+
+    private static final List<String> INSTITUTION_START = List.of(
+            "Firma", "Architekt");
+
+    private static final List<String> INSTITUTION_END = List.of(
+            "GmbH");
+
+    private static final List<String> GROUP_START = List.of(
+            "Familie", "Comité", "Comite", "Geschwister", "Gesellschafter",
+            "Garde", "Mitarbeiter");
+
+    private static final List<String> GROUP_CONTAINS = List.of(
+            "Eltern", "Kinder", "Schwiegereltern");
+
+    public static PersonType classify(String rawName) {
+        if (rawName == null || rawName.isBlank()) return PersonType.PERSON;
+
+        String trimmed = rawName.trim();
+        String lower = trimmed.toLowerCase();
+
+        for (String keyword : SKIP_KEYWORDS) {
+            if (lower.startsWith(keyword.toLowerCase())) return PersonType.SKIP;
+        }
+
+        for (String keyword : INSTITUTION_START) {
+            if (lower.startsWith(keyword.toLowerCase())) return PersonType.INSTITUTION;
+        }
+        for (String keyword : INSTITUTION_END) {
+            if (lower.endsWith(keyword.toLowerCase())) return PersonType.INSTITUTION;
+        }
+        if (lower.endsWith(" co") || lower.endsWith(" co.")) return PersonType.INSTITUTION;
+
+        for (String keyword : GROUP_START) {
+            if (lower.startsWith(keyword.toLowerCase())) return PersonType.GROUP;
+        }
+        for (String keyword : GROUP_CONTAINS) {
+            if (containsWord(lower, keyword.toLowerCase())) return PersonType.GROUP;
+        }
+
+        return PersonType.PERSON;
+    }
+
+    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;
+    }
+}