fix(document): restore pure-text-relevance FTS fast path past undated count

The global undated-count rework moved the pure-text-RELEVANCE shortcut
into runSearch, where it ran after the unconditional
findAllMatchingIdsByFts call. That routed pure-text relevance through the
in-memory id path and returned empty match data, breaking FTS rank order
and snippet/offset enrichment.

Hoist the shortcut back to the top of searchDocuments so it short-circuits
to findFtsPageRaw before findAllMatchingIdsByFts, while still computing the
global undatedCount for all non-fast-path searches.

Refs #668

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

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

@@ -669,6 +669,18 @@ public class DocumentService {
     public DocumentSearchResult searchDocuments(String text, LocalDate from, LocalDate to, UUID sender, UUID receiver, List<String> tags, String tagQ, DocumentStatus status, DocumentSort sort, String dir, TagOperator tagOperator, boolean undated, Pageable pageable) {
         boolean hasText = StringUtils.hasText(text);
 
+        // Pure-text RELEVANCE: push pagination + ts_rank ordering into SQL — skip
+        // findAllMatchingIdsByFts entirely (ADR-008). This must run BEFORE any
+        // findAllMatchingIdsByFts call so the fast path is preserved. An active undated
+        // filter must NOT take this path: it bypasses buildSearchSpec, so the
+        // undatedOnly predicate would be silently dropped. By definition this path has
+        // no date/sender/receiver/tag/status filters, and undated documents are valid
+        // FTS hits already folded into the ranked page, so there is no separate undated
+        // count to report here.
+        if (!undated && isPureTextRelevance(hasText, sort, from, to, sender, receiver, tags, tagQ, status)) {
+            return relevanceSortedPageFromSql(text, pageable);
+        }
+
         List<UUID> rankedIds = null;
         if (hasText) {
             rankedIds = documentRepository.findAllMatchingIdsByFts(text);
@@ -706,13 +718,8 @@ public class DocumentService {
                                            List<String> tags, String tagQ, DocumentStatus status,
                                            DocumentSort sort, String dir, TagOperator tagOperator,
                                            boolean undated, Pageable pageable) {
-        // Pure-text RELEVANCE: push pagination into SQL — skip findAllMatchingIdsByFts entirely (ADR-008).
-        // An active undated filter must NOT take this path: it bypasses buildSearchSpec, so the
-        // undatedOnly predicate would be silently dropped.
-        if (!undated && isPureTextRelevance(hasText, sort, from, to, sender, receiver, tags, tagQ, status)) {
-            return relevanceSortedPageFromSql(text, pageable);
-        }
-
+        // The pure-text RELEVANCE fast path is handled by the caller (searchDocuments)
+        // before findAllMatchingIdsByFts runs, so it never reaches here (ADR-008).
         Specification<Document> spec = buildSearchSpec(
                 hasText, rankedIds, from, to, sender, receiver, tags, tagQ, status, tagOperator, undated);