fix(PROJ-44): SNIPPET via SELECT statt CALL SNIPPETS (Go MySQL-Treiber-Kompatibilitaet)

CALL SNIPPETS liefert einen anderen MySQL-Pakettyp als SELECT, den der
Go-Treiber (go-sql-driver/mysql) mit "malformed packet" ablehnt.
SELECT SNIPPET(text, query) FROM table ist die korrekte Alternative
fuer Manticore 25.

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

internal/index/manticore_snippet.go

@@ -102,14 +102,12 @@ func (idx *manticoreIndex) buildSnippet(mailID, query, matchField string) (strin
 		return "", nil
 	}
 
-	// CALL SNIPPETS(text, table, query).
-	// Manticore 25+ accepts exactly 3 arguments; options-as-extra-args were
-	// removed in this version. Default markers are already <b>/<b/>, which is
-	// what we need. Manticore returns a single-column, single-row result.
-	row := idx.db.QueryRow(
-		`CALL SNIPPETS(?, ?, ?)`,
-		source, idx.table, query,
-	)
+	// SELECT SNIPPET(text, query) FROM table.
+	// Manticore 25+ supports SNIPPET() as a SELECT expression; CALL SNIPPETS
+	// returns a different packet type that the Go MySQL driver mishandles
+	// ("malformed packet"). Default markers are <b>/<b/>, no options needed.
+	q := fmt.Sprintf(`SELECT SNIPPET(?, ?) FROM %s LIMIT 1`, idx.table)
+	row := idx.db.QueryRow(q, source, query)
 	var snippet string
 	if err := row.Scan(&snippet); err != nil {
 		return "", fmt.Errorf("call snippets %s: %w", idx.table, err)