Feed links are followed only when they are web addresses (#326)

An item's link and an enclosure's URL are the publisher's, stored as
written, and the page put them in href and window.open through esc(),
which escapes characters, not schemes: a javascript: or data: link
survived as Open the original, View in a new tab (for a file not on
disk), the Directory's item links and the v key. Show notes already
lose those schemes to ammonia; these four sinks were the exception.

webUrl() passes http(s) only, and each sink goes through it. A link
that fails it shows no link, as an item with none does.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/src/dialogs.ts

@@ -281,7 +281,7 @@ async function fillShow(box: HTMLElement,p: DirFeed){
   list.innerHTML=items.length?items.map(e=>{
     const name=entryName(e), text=name.derived?'':plainText(e.description).slice(0,500);
     const when=[dateOf(e.published),e.duration&&clock(e.duration)].filter(Boolean);
-    return `<article class="lep"><b>${e.link?`<a href="${esc(e.link)}" target="_blank" rel="noopener">${esc(name.text)}</a>`:esc(name.text)}</b>`
+    return `<article class="lep"><b>${webUrl(e.link)?`<a href="${esc(webUrl(e.link))}" target="_blank" rel="noopener">${esc(name.text)}</a>`:esc(name.text)}</b>`
       +(text?`<p>${esc(text)}</p>`:'')
       +(when.length?`<small>${when.map(s=>`<span>${s}</span>`).join('<span class="dot"></span>')}</small>`:'')+'</article>';
   }).join(''):'<p class="hint">Nothing read from it yet. The directory checks each feed every few hours.</p>';