Batch of accessibility and touch fixes from the audit

- Esc closes whichever panel a card has open and returns focus to the cell that
  owns it; opening a confirm row moves focus to its primary button, so the
  announcement is deterministic and tab order stays inside the confirm.
- The inline error scrolls itself into view and no longer self-destructs after
  5s: this reader gets interrupted mid-tap, and an expiring notice left a failed
  write with no trace at all. It clears on the next request from that card.
- Every tab clears 44px wide (All was 15.25); desktop action cells go 40 -> 44.
- login.html's error gets role="alert".
- The card monogram carries its own aria-hidden — Chromium exposes it through
  the cover link's, because that link is programmatically focusable.
- The busy bar ends its travel flush with the card edge, so .card.htmx-request
  no longer needs overflow: hidden and cannot clip a panel mid-request.

Verified at 390 and 1280 in both themes; detector over templates+static reports
only the two known Instrument Serif false positives.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

backend/static/filter.js

@@ -101,9 +101,26 @@ function toggleChapterForm(key) {
 // cell share it.
 function toggleConfirmRow(key, kind) {
   var cls = { archive: ".box", finish: ".finish", remove: ".remove" }[kind];
-  togglePanel(key, "confirm-" + kind + "-" + key, ".actions " + cls);
+  var row = togglePanel(key, "confirm-" + kind + "-" + key, ".actions " + cls);
+  // Focus the answer rather than trusting aria-live on a container that merely
+  // unhides: it makes the announcement deterministic, keeps tab order inside
+  // the confirm instead of running on into the next card, and means the row
+  // cannot be opened and scrolled past unnoticed.
+  if (row && !row.hidden) row.querySelector("button").focus();
 }
 
+// Esc closes whichever panel this card has open and hands focus back to the
+// cell that owns it — otherwise the only way out is finding that exact cell
+// again.
+document.addEventListener("keydown", function (e) {
+  if (e.key !== "Escape" || !e.target.closest) return;
+  var card = e.target.closest(".card");
+  var owner = card && card.querySelector(".actions .open");
+  if (!owner) return;
+  closeCardPanels(card.id.replace(/^card-/, ""));
+  owner.focus();
+});
+
 // A failed favourite/chapter/delete request leaves the card in place (htmx
 // does not swap on a non-2xx response) but otherwise gives no sign anything
 // went wrong. Surface it inline instead of leaving the tap looking ignored.
@@ -121,12 +138,23 @@ function toggleConfirmRow(key, kind) {
       slot.append(" ", a);
     }
     slot.hidden = false;
-    clearTimeout(slot._hideTimer);
-    slot._hideTimer = setTimeout(function () {
-      slot.hidden = true;
-    }, linkHref ? 30000 : 5000);
+    // No self-destruct timer: this reader gets interrupted mid-tap, and a
+    // notice that expires after 5s leaves a failed write with no trace at all
+    // — the star is back off and nothing says why. The notice stays until the
+    // next request from this card clears it (or a successful one swaps the
+    // whole card away).
+    slot.scrollIntoView({
+      block: "nearest",
+      behavior: matchMedia("(prefers-reduced-motion: reduce)").matches ? "auto" : "smooth",
+    });
   }
 
+  document.body.addEventListener("htmx:beforeRequest", function (e) {
+    var card = e.detail.elt.closest(".card");
+    var slot = card && card.querySelector(".error-inline");
+    if (slot) slot.hidden = true;
+  });
+
   // The handlers answer a bad value with http.Error, i.e. a short plain-text
   // line — worth showing verbatim. Anything long or HTML-ish is an error page,
   // not a reason, so fall back to the generic copy.