test(search): add DocumentSearchEnrichmentTest for findEnrichmentData native query

Tests lateral join best-block selection, chr(1)/chr(2) headline delimiters,
sender/receiver/tag match flags, and null cases for missing relations.

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

backend/src/main/java/org/raddatz/familienarchiv/repository/DocumentRepository.java

@@ -89,4 +89,55 @@ public interface DocumentRepository extends JpaRepository<Document, UUID>, JpaSp
             """)
     List<UUID> findRankedIdsByFts(@Param("query") String query);
 
+    /**
+     * Returns match-enrichment data for a set of documents identified by their IDs.
+     * Each row contains (in column order):
+     * <ol>
+     *   <li>UUID   — document id</li>
+     *   <li>String — title headline with \x01/\x02 delimiters around matched terms</li>
+     *   <li>String — best-ranked matching transcription block text, or null</li>
+     *   <li>Boolean — whether the sender's name matched the query</li>
+     *   <li>String — comma-separated matched receiver UUIDs, or null</li>
+     *   <li>String — comma-separated matched tag UUIDs, or null</li>
+     * </ol>
+     * Short-circuit before calling this method when {@code ids} is empty or {@code query} is blank.
+     */
+    @Query(nativeQuery = true, value = """
+            SELECT
+                d.id,
+                ts_headline('german', d.title, websearch_to_tsquery('german', :query),
+                    'StartSel=' || chr(1) || ',StopSel=' || chr(2) || ',HighlightAll=true')
+                    AS title_headline,
+                best_block.text AS transcription_snippet,
+                (s.id IS NOT NULL AND
+                 to_tsvector('german', COALESCE(s.first_name, '') || ' ' || COALESCE(s.last_name, ''))
+                     @@ websearch_to_tsquery('german', :query))
+                    AS sender_matched,
+                (SELECT string_agg(r.id::text, ',')
+                 FROM document_receivers dr
+                 JOIN persons r ON r.id = dr.person_id
+                 WHERE dr.document_id = d.id
+                   AND to_tsvector('german', COALESCE(r.first_name, '') || ' ' || r.last_name)
+                           @@ websearch_to_tsquery('german', :query)
+                ) AS matched_receiver_ids,
+                (SELECT string_agg(t.id::text, ',')
+                 FROM document_tags dt
+                 JOIN tag t ON t.id = dt.tag_id
+                 WHERE dt.document_id = d.id
+                   AND to_tsvector('german', t.name) @@ websearch_to_tsquery('german', :query)
+                ) AS matched_tag_ids
+            FROM documents d
+            LEFT JOIN persons s ON s.id = d.sender_id
+            LEFT JOIN LATERAL (
+                SELECT tb.text
+                FROM transcription_blocks tb
+                WHERE tb.document_id = d.id
+                  AND to_tsvector('german', tb.text) @@ websearch_to_tsquery('german', :query)
+                ORDER BY ts_rank(to_tsvector('german', tb.text), websearch_to_tsquery('german', :query)) DESC
+                LIMIT 1
+            ) best_block ON true
+            WHERE d.id IN :ids
+            """)
+    List<Object[]> findEnrichmentData(@Param("ids") Collection<UUID> ids, @Param("query") String query);
+
 }