Refresh the FlowLink tap closure in updateUIView

[TaylorAanenson]

The problem

GestureContainer.makeCoordinator() stores onTap on the coordinator, and updateUIView is empty. SwiftUI creates a coordinator once per representable and reuses it across updates, so the UIButton keeps invoking the very first onTap it was handed.

That closure is { trigger() }, capturing the FlowLink struct from its first body evaluation — including its value and its label. Every later body pass builds a new struct that the button never sees.

Symptoms

For a FlowLink whose row is refreshed in place — same identity, new content — two things go wrong and neither is fixable from the call site:

1. The pushed value is stale. trigger() appends the first-render value, so the destination receives outdated data. This bites hard in the common pattern of rendering a cached list and then swapping in a fetched payload under the same id: taps open the cached copy of a row for the rest of the session.
2. The transition snapshot is stale. initSnapshots() renders the first-render label, so the image painted over the zoom shows content the row no longer displays. retakeSnapshots: true doesn't help — it faithfully re-renders the stale label.

Repro

A list whose rows come from a cache and are then replaced by fetched data under the same identity. Render it, let the fetch land so a row visibly updates, then tap that row — the destination gets the pre-fetch value. Deleting the cache so the row's first render is the fetched payload makes the same tap behave correctly.

The fix

One line, matching the standard UIViewRepresentable contract of pushing current state in updateUIView. The isPressed binding is left alone: it targets a stable @State box, so it doesn't go stale the way the escaping closure does.