feat(rag): add doc-summary pre-filtering to DbnLegalToolsService::search

Before chunk retrieval, embed the query against bnl_doc_summaries Qdrant
collection to identify the most semantically relevant documents. The
resulting document IDs are passed as shared_doc_ids to searchAll(),
narrowing the shared-corpus chunk search to those documents only.

Applied to the 'shared' and 'both' scope paths (not 'private', which
has no shared corpus). Non-fatal: on any error preFilterDocIds stays
empty and search falls back to current unfiltered chunk retrieval.

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

includes/LegalTools.php

@@ -70,6 +70,18 @@ final class DbnLegalToolsService
                 // Retrieval still works in keyword mode without gateway config.
             }
 
+            // Doc-summary pre-pass: embed query → search bnl_doc_summaries → narrow shared chunks
+            // to the most semantically relevant documents. Non-fatal: empty = no filter applied.
+            $preFilterDocIds = [];
+            if ($scope !== 'private') {
+                try {
+                    $preRag = new ClientRagPipeline((int)$client['id'], $gatewayUrl, 30);
+                    $preFilterDocIds = $preRag->searchDocSummaries($query);
+                } catch (Throwable) {
+                    // fall through — unfiltered chunk search
+                }
+            }
+
             if ($scope === 'private') {
                 // Search only the user's personal corpus
                 if ($personalClientId > 0) {
@@ -93,6 +105,7 @@ final class DbnLegalToolsService
                     'search_method' => $searchMethod,
                     'min_private' => 0,
                     'include_beta_website' => true,
+                    'shared_doc_ids' => $preFilterDocIds ?: null,
                 ]));
             } else {
                 // 'both': shared library + personal corpus merged and re-ranked by score
@@ -105,6 +118,7 @@ final class DbnLegalToolsService
                     'search_method' => $searchMethod,
                     'min_private' => 0,
                     'include_beta_website' => true,
+                    'shared_doc_ids' => $preFilterDocIds ?: null,
                 ]));
 
                 $privateChunks = [];