feat(search): add NlpExtraction record, NlpClient and NlpHealthClient interfaces

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

backend/src/main/java/org/raddatz/familienarchiv/search/NlpClient.java

@@ -0,0 +1,5 @@
+package org.raddatz.familienarchiv.search;
+
+public interface NlpClient {
+    NlpExtraction parse(String query, String lang);
+}

backend/src/main/java/org/raddatz/familienarchiv/search/NlpExtraction.java

@@ -0,0 +1,14 @@
+package org.raddatz.familienarchiv.search;
+
+import java.time.LocalDate;
+import java.util.List;
+
+record NlpExtraction(
+        List<String> personNames,
+        String personRole,
+        LocalDate dateFrom,
+        LocalDate dateTo,
+        List<String> keywords,
+        String rawQuery
+) {
+}

backend/src/main/java/org/raddatz/familienarchiv/search/NlpHealthClient.java

@@ -0,0 +1,5 @@
+package org.raddatz.familienarchiv.search;
+
+public interface NlpHealthClient {
+    boolean isHealthy();
+}