feat(search): surface summary snippet when summary matched the query

Add a summary_snippet column to findEnrichmentData using ts_headline on
documents.summary, only when the summary's tsvector matches the query.
Expose it via SearchMatchData.summarySnippet / summaryOffsets and render
a "Zusammenfassung" / "Summary" / "Resumen" labelled row in the document
list — identical treatment to the transcription snippet row.

Fixes the case where a document appeared in search results with no
visible match explanation (e.g. searching "frucht" found a document
whose summary mentioned "Früchte").

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

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

@@ -7,8 +7,8 @@ import java.util.UUID;
 
 /**
  * Match signals for a single document in a full-text search result.
- * All fields are non-null except {@code transcriptionSnippet}, which is null
- * when no transcription block matched the query.
+ * All fields are non-null except {@code transcriptionSnippet} and {@code summarySnippet},
+ * which are null when the respective field did not match the query.
  */
 public record SearchMatchData(
         /**
@@ -46,10 +46,22 @@ public record SearchMatchData(
          * Empty when no transcription block matched or the snippet has no highlights.
          */
         @Schema(requiredMode = Schema.RequiredMode.REQUIRED)
-        List<MatchOffset> snippetOffsets
+        List<MatchOffset> snippetOffsets,
+
+        /**
+         * Highlighted summary excerpt, or null if the summary did not match the query.
+         */
+        String summarySnippet,
+
+        /**
+         * Character offsets of highlighted terms within the summary snippet.
+         * Empty when the summary did not match or has no highlights.
+         */
+        @Schema(requiredMode = Schema.RequiredMode.REQUIRED)
+        List<MatchOffset> summaryOffsets
 ) {
     /** Canonical "no match data" value for a single document. */
     public static SearchMatchData empty() {
-        return new SearchMatchData(null, List.of(), false, List.of(), List.of(), List.of());
+        return new SearchMatchData(null, List.of(), false, List.of(), List.of(), List.of(), null, List.of());
     }
 }

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

@@ -607,14 +607,18 @@ public class DocumentService {
             Boolean senderMatched = (Boolean) row[3];
             String receiverIdsStr = (String) row[4];
             String tagIdsStr = (String) row[5];
+            String summaryHeadline = (String) row[6];
             ParsedHighlight snippet = parseHighlight(snippetHeadline);
+            ParsedHighlight summary = parseHighlight(summaryHeadline);
             result.put(docId, new SearchMatchData(
                     snippet != null ? snippet.cleanText() : null,
                     parseTitleOffsets(titleHeadline),
                     senderMatched != null && senderMatched,
                     parseUUIDs(receiverIdsStr),
                     parseUUIDs(tagIdsStr),
-                    snippet != null ? snippet.offsets() : List.of()
+                    snippet != null ? snippet.offsets() : List.of(),
+                    summary != null ? summary.cleanText() : null,
+                    summary != null ? summary.offsets() : List.of()
             ));
         }
         return result;

backend/src/test/java/org/raddatz/familienarchiv/controller/DocumentControllerTest.java

@@ -125,7 +125,7 @@ class DocumentControllerTest {
                 .status(DocumentStatus.UPLOADED)
                 .build();
         var matchData = new org.raddatz.familienarchiv.dto.SearchMatchData(
-                "Er schrieb einen langen Brief", List.of(), false, List.of(), List.of(), List.of());
+                "Er schrieb einen langen Brief", List.of(), false, List.of(), List.of(), List.of(), null, List.of());
         when(documentService.searchDocuments(any(), any(), any(), any(), any(), any(), any(), any(), any(), any()))
                 .thenReturn(DocumentSearchResult.withMatchData(List.of(doc), Map.of(docId, matchData)));
 

backend/src/test/java/org/raddatz/familienarchiv/dto/DocumentSearchResultTest.java

@@ -36,7 +36,7 @@ class DocumentSearchResultTest {
     @Test
     void withMatchData_exposes_match_data_map() {
         UUID id = UUID.randomUUID();
-        SearchMatchData data = new SearchMatchData("snippet", List.of(), false, List.of(), List.of(), List.of());
+        SearchMatchData data = new SearchMatchData("snippet", List.of(), false, List.of(), List.of(), List.of(), null, List.of());
         DocumentSearchResult result = DocumentSearchResult.withMatchData(List.of(doc(id)), Map.of(id, data));
 
         assertThat(result.matchData()).containsKey(id);

backend/src/test/java/org/raddatz/familienarchiv/dto/SearchMatchDataTest.java

@@ -10,7 +10,7 @@ class SearchMatchDataTest {
 
     @Test
     void transcription_snippet_is_nullable() {
-        SearchMatchData data = new SearchMatchData(null, List.of(), false, List.of(), List.of(), List.of());
+        SearchMatchData data = new SearchMatchData(null, List.of(), false, List.of(), List.of(), List.of(), null, List.of());
 
         assertThat(data.transcriptionSnippet()).isNull();
     }
@@ -35,6 +35,8 @@ class SearchMatchDataTest {
                 true,
                 List.of(),
                 List.of(),
+                List.of(),
+                null,
                 List.of()
         );
 
@@ -58,7 +60,9 @@ class SearchMatchDataTest {
                 false,
                 List.of(),
                 List.of(),
-                List.of(offset)
+                List.of(offset),
+                null,
+                List.of()
         );
         assertThat(data.snippetOffsets()).containsExactly(offset);
     }