Detach DuckLake before closing connection to release RDS connections

When a client disconnects, explicitly DETACH the ducklake catalog before
closing the DuckDB connection. This ensures the DuckLake extension properly
releases its connection to the RDS metadata store, preventing connection leaks.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Author: EDsCODE

server/conn.go

@@ -88,6 +88,12 @@ func (c *clientConn) serve() error {
 	// Ensure the database connection is closed when this client disconnects
 	defer func() {
 		if c.db != nil {
+			// Detach DuckLake to release the RDS metadata connection
+			if c.server.cfg.DuckLake.MetadataStore != "" {
+				if _, err := c.db.Exec("DETACH ducklake"); err != nil {
+					log.Printf("Warning: failed to detach DuckLake for user %q: %v", c.username, err)
+				}
+			}
 			c.db.Close()
 			log.Printf("Closed DuckDB connection for user %q", c.username)
 		}