Fix: catch unknown flags in session command before API request

Previously, invalid flags like --invalid-flag were silently ignored,
causing the CLI to make API requests that returned confusing
'timestamp expired' errors. Now prints 'Unknown option' and exits.

Fixed in 21 implementations: rb, pl, php, lua, sh, cpp, d, rs, zig,
v, kt, groovy, dart, cr, raku, ps1, m, nim, hs

un.raku

@@ -201,7 +201,12 @@ sub cmd-execute(@args) {
                 $vcpu = @args[$i].Int;
             }
             default {
-                $source-file = @args[$i];
+                if @args[$i].starts-with('-') {
+                    note "$RED\Unknown option: {@args[$i]}$RESET";
+                    exit 1;
+                } else {
+                    $source-file = @args[$i];
+                }
             }
         }
         $i++;