fix(canvas): ExternalConnectModal redundant null check on Dialog.Root open prop

[Molecule-Platform-Evolvement-Manager]

Addresses github-code-quality finding on PR #2064:

> Comparison between inconvertible types
> Variable 'info' cannot be of type null, but it is compared to
> an expression of type null.

By line 75, `info` has been narrowed to non-null via the
`if (!info) return null;` guard at line 56 — so `open={info !== null}`
always evaluates to `true`. Switch to JSX shorthand `open` for
clarity and to silence the static check.

Behaviorally identical; the modal still opens whenever the parent
renders this component (which only happens with non-null info).

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

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

canvas/src/components/ExternalConnectModal.tsx

@@ -72,7 +72,7 @@ export function ExternalConnectModal({ info, onClose }: Props) {
   );
 
   return (
-    <Dialog.Root open={info !== null} onOpenChange={(o) => !o && onClose()}>
+    <Dialog.Root open onOpenChange={(o) => !o && onClose()}>
       <Dialog.Portal>
         <Dialog.Overlay className="fixed inset-0 bg-black/60 z-50" />
         <Dialog.Content className="fixed left-1/2 top-1/2 z-50 w-[min(720px,92vw)] -translate-x-1/2 -translate-y-1/2 rounded-xl bg-zinc-900 border border-zinc-700 p-6 shadow-2xl">