Stop a listing page from rewriting the next one's grid after navigation.

Switching between /mints, /fedimints and /lnurl-mints showed the right list
for a moment and then flashed back to the previous ecosystem's mints. The
client router keeps every page's script alive, and onReady re-runs each
setup on every arrival, so a visited page's setup also ran on the next page.
All three grids were marked with the same bare data-mint-grid, so the stale
setup found the new grid, fetched its own type and overwrote it.

Mark and query each grid by ecosystem (data-mint-grid="cashu" etc.), the way
the home page already scopes data-home-grid, so a stale setup finds nothing
and bails. Skip the render in hydrateMintGrid when the grid has already been
detached by the router. Document the re-run-everywhere contract on onReady,
and add a static wiring test so a bare marker cannot come back.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

web/src/scripts/reveal.ts

@@ -208,6 +208,15 @@ export function armSharedTransitions(): void {
  * only does its work at module scope is dead after the first navigation. It does fire
  * `astro:page-load` on every arrival, including the first, but on the first it waits
  * for `window.load`, which is far too late to be the only trigger. Hence both.
+ *
+ * The listener is never removed, on purpose: a layout island (the language switcher,
+ * the login dialog) has DOM on every page, and this is what keeps it alive. The flip
+ * side is that `setup` runs on *every* page the router swaps in, not only pages that
+ * include the script. A page-level script must therefore look its DOM up by a marker
+ * unique to that page — `data-mint-grid="cashu"`, `data-home-grid="fedimint"` — and do
+ * nothing when the marker is absent. A marker shared between pages means a stale page's
+ * setup finds the current page's DOM and rewrites it: the listing pages once flashed
+ * back to the previous ecosystem's mints for exactly that reason.
  */
 export function onReady(setup: () => void): void {
   let done = false;