fix: use stateful MCP sessions for public clients

Stateless mode omitted Mcp-Session-Id and broke initialize→tools/call
flows used by public mcp.verae.ai clients.

cmd/verae-mcp-timestamping-server/main.go

@@ -57,8 +57,10 @@ func main() {
 			AuthPath:      cfg.AuthPath,
 			GlobalURL:     cfg.GlobalURL,
 			RequireBearer: cfg.RequireBearer,
-			JSONResponse:  true,
-			Stateless:     true,
+			// Stateful sessions + JSON responses match public mcp.verae.ai clients
+			// (Mcp-Session-Id after initialize). Stateless broke tools/call for those clients.
+			JSONResponse: true,
+			Stateless:    false,
 		})
 		if err != nil {
 			log.Fatalf("server: %v", err)