Fix toggling all checkboxes of failed imports:

- Rename classes and function to something more descriptive.
- Listen to the element checked status instead of a click on a non‑focusable element.
- Use specific DOM targets instead of relying on the DOM ancestor tree.
- Add a skip‑link to the end of the list and avoid tabbing through all failed items.
- Update related i18n strings in French.
- Avoid having the label on the whole width to prevent accidental click.
- Move `fieldset` out of `ul`.

bookwyrm/static/css/format.css

@@ -156,3 +156,35 @@
     content: "\e905";
     right: 0;
 }
+
+/**
+ * Accessibility (a11y)
+ ============================================================================ */
+
+/**
+ * Skip links
+ *
+ * @see https://webaim.org/styles/main.css
+ ---------------------------------------------------------------------------- */
+.skip-link {
+    position: absolute;
+    opacity: 0;
+    z-index: 100;
+    padding: 6px;
+    border: 1px solid white;
+    color: white;
+    background: #BF1722;
+    transition: opacity 1s ease-out;
+}
+
+.skip-link:focus {
+    opacity: 1;
+    outline-color: transparent;
+    transition: opacity .1s ease-in;
+}
+
+@media (prefers-reduced-motion: reduce) {
+    .skip-link {
+        transition-duration: 0.001ms !important;
+    }
+}