feat(a11y): R9 focus foundation — glass shadow fix, focus-visible ring, highlight/selected split

S1 — recipe foundation:
- Move .glass/.glass-card/.glass-menu into @layer components so a JSX shadow-* utility overrides the
  glass box-shadow again; the ~9 dead shadow-* on glass surfaces (modals, menus, save-bar, chat) now
  paint their intended drop-shadow. Perf-mode and :hover overrides stay unlayered so they still win.
- Add a .selectable recipe: the hover tint menu/list rows already use, PLUS the app-wide
  focus-visible ring that was missing on non-input controls (the biggest a11y gap).
- Split the popover roving highlight from the selected state (AnchoredPopover): a selected/checked
  PopoverItem now gets a ring ONLY, so its resting paint (bg-accent fill / text-accent / checkbox)
  survives being highlighted instead of downgrading to a 35% tint or being recoloured. Fixes the 4
  review findings deferred from R10-S0 generically; drops the leftover per-consumer data-active ring
  in tableHeader.

S2 — worst offenders:
- Account-menu trigger + switch/add/sign-out rows adopt .selectable (visible keyboard focus).
- Saved-views rows: group-focus-within reveals the hover-only action buttons for keyboard users;
  aria-current on the active row; focus-visible ring on every button.
- The 3 invisible-focus inputs get an accent focus ring: SearchBar + ShareDialog via focus-within on
  the glass pill/row, AboutCell via focus-visible on the trigger.

Deferred to a later R9 sprint: the full unification of all ~14 selection idioms, a shared <NavItem>,
and .is-current/.chip recipes (no consumer yet in this pass).

Verified: tsc/eslint/prettier/knip/vitest (79) green; browser computed-style checks confirm the glass
shadow now wins, the focus outlines render (2px accent), and the split renders (selected ring-only,
unselected fill).

frontend/src/components/SavedViewsWidget.tsx

@@ -288,14 +288,15 @@ function ViewRow({
         {...attributes}
         {...listeners}
         title={t("views.reorder")}
-        className="p-1 text-muted/60 hover:text-muted cursor-grab touch-none shrink-0"
+        className="p-1 text-muted/60 hover:text-muted cursor-grab touch-none shrink-0 rounded-sm outline-hidden focus-visible:outline-2 focus-visible:outline-accent/60"
       >
         <GripVertical className="w-3.5 h-3.5" />
       </button>
       <button
         onClick={onApply}
         title={t("views.apply")}
-        className={`flex-1 min-w-0 text-left text-xs py-1 truncate ${
+        aria-current={active ? "true" : undefined}
+        className={`flex-1 min-w-0 text-left text-xs py-1 truncate rounded-sm outline-hidden focus-visible:outline-2 focus-visible:outline-accent/60 ${
           active ? "text-accent font-medium" : "text-fg"
         }`}
       >
@@ -305,10 +306,10 @@ function ViewRow({
         <button
           onClick={onToggleDefault}
           title={view.is_default ? t("views.isDefault") : t("views.makeDefault")}
-          className={`p-1 rounded transition ${
+          className={`p-1 rounded outline-hidden transition focus-visible:outline-2 focus-visible:outline-accent/60 ${
             view.is_default
               ? "text-accent"
-              : "text-muted opacity-0 group-hover:opacity-100 hover:text-accent"
+              : "text-muted opacity-0 group-hover:opacity-100 group-focus-within:opacity-100 hover:text-accent"
           }`}
         >
           <Star className={`w-3.5 h-3.5 ${view.is_default ? "fill-current" : ""}`} />
@@ -316,21 +317,21 @@ function ViewRow({
         <button
           onClick={onShare}
           title={t("views.share")}
-          className="p-1 rounded-sm text-muted opacity-0 group-hover:opacity-100 hover:text-fg transition"
+          className="p-1 rounded-sm text-muted opacity-0 group-hover:opacity-100 group-focus-within:opacity-100 hover:text-fg transition outline-hidden focus-visible:outline-2 focus-visible:outline-accent/60"
         >
           <Share2 className="w-3.5 h-3.5" />
         </button>
         <button
           onClick={onStartRename}
           title={t("views.rename")}
-          className="p-1 rounded-sm text-muted opacity-0 group-hover:opacity-100 hover:text-fg transition"
+          className="p-1 rounded-sm text-muted opacity-0 group-hover:opacity-100 group-focus-within:opacity-100 hover:text-fg transition outline-hidden focus-visible:outline-2 focus-visible:outline-accent/60"
         >
           <Pencil className="w-3.5 h-3.5" />
         </button>
         <button
           onClick={onDelete}
           title={t("views.delete")}
-          className="p-1 rounded-sm text-muted opacity-0 group-hover:opacity-100 hover:text-red-400 transition"
+          className="p-1 rounded-sm text-muted opacity-0 group-hover:opacity-100 group-focus-within:opacity-100 hover:text-red-400 transition outline-hidden focus-visible:outline-2 focus-visible:outline-accent/60"
         >
           <Trash2 className="w-3.5 h-3.5" />
         </button>