fix(PROJ-44): snippet + match_field in enrichedHit-Struct und JSON-Response verdrahten

Die enrichedHit-Struct in search_handlers.go fehlten die PROJ-44-Felder
Snippet und MatchField, sodass die vom Index berechneten Snippets in der
API-Response verworfen wurden.

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

internal/api/search_handlers.go

@@ -143,6 +143,8 @@ func (s *Server) handleSearch(w http.ResponseWriter, r *http.Request) {
 		HasAttachments bool    `json:"has_attachments"`
 		ThreadID       string  `json:"thread_id,omitempty"`
 		ThreadSize     int     `json:"thread_size,omitempty"`
+		Snippet        string  `json:"snippet,omitempty"`    // PROJ-44: HTML excerpt with <b>match</b> tags
+		MatchField     string  `json:"match_field,omitempty"` // PROJ-44: subject|body|attachment_text|...
 	}
 
 	// auditor role: restrict results to mails with no tenant assignment.
@@ -180,7 +182,7 @@ func (s *Server) handleSearch(w http.ResponseWriter, r *http.Request) {
 
 	enriched := make([]enrichedHit, 0, len(result.Hits))
 	for _, h := range result.Hits {
-		eh := enrichedHit{ID: h.ID, Score: h.Score}
+		eh := enrichedHit{ID: h.ID, Score: h.Score, Snippet: h.Snippet, MatchField: h.MatchField}
 		if raw, err := s.store.Load(h.ID); err == nil {
 			eh.Size = int64(len(raw))
 			if pm, err := mailparser.Parse(raw); err == nil {