fix(a11y): every side-panel pin names its panel; the tab under an open card leaves the tree

The card's own pin and the drawer's still said 'Unpin panel' / 'Pin panel open' after the edge tab
learned the title (F6). Naming them too made two buttons share a name, because the invisible tab
under an open card was still in the accessibility tree: it is now aria-hidden as well as out of
the Tab order. The generic sidebar.pin / unpin keys are gone.

frontend/src/components/ui/SidePanel.drawer.dom.test.tsx

@@ -95,8 +95,12 @@ describe("SidePanel · the tab under an open card", () => {
       disconnect() {}
     } as unknown as typeof ResizeObserver;
     mount(false); // pinned
-    const tab = screen.getByRole("button", { name: "sidebar.unpinNamed:Filters", hidden: true });
+    // The card's own pin is the one control by that name; the tab under it is out of the tree too.
+    const tab = document.querySelector<HTMLElement>(
+      '[aria-hidden="true"][aria-label="sidebar.unpinNamed:Filters"]',
+    )!;
     expect(tab.tabIndex).toBe(-1);
+    expect(screen.getAllByRole("button", { name: "sidebar.unpinNamed:Filters" })).toHaveLength(1);
     cleanup();
     mount(true);
     expect(screen.getByRole("button", { name: "sidebar.pinNamed:Filters" }).tabIndex).toBe(0);
@@ -113,7 +117,7 @@ describe("SidePanel · on touch", () => {
     expect(dialog.textContent).toContain("panel body");
     expect(onToggleCollapse).not.toHaveBeenCalled();
     // Below 1024 a pinned panel would leave the content no room: no pin in the drawer.
-    expect(screen.queryByRole("button", { name: "sidebar.pin" })).toBeNull();
+    expect(screen.queryByRole("button", { name: "sidebar.pinNamed:Filters" })).toBeNull();
     fireEvent.keyDown(window, { key: "Escape" });
     expect(screen.queryByRole("dialog")).toBeNull();
   });
@@ -129,7 +133,7 @@ describe("SidePanel · on touch", () => {
     stubMedia({ coarse: true, narrow: false, wide: true });
     const { onToggleCollapse } = mount();
     fireEvent.click(screen.getByRole("button", { name: "sidebar.openPanel:Filters" }));
-    fireEvent.click(screen.getByRole("button", { name: "sidebar.pin" }));
+    fireEvent.click(screen.getByRole("button", { name: "sidebar.pinNamed:Filters" }));
     expect(onToggleCollapse).toHaveBeenCalledOnce();
     expect(screen.queryByRole("dialog")).toBeNull();
   });

frontend/src/components/ui/SidePanel.tsx

@@ -160,7 +160,10 @@ export default function SidePanel({
                   );
               }
         }
+        // Under an open card the tab is transparent and inert: out of the Tab order AND of the
+        // accessibility tree, where it would repeat the card's own pin button by name.
         tabIndex={expanded ? -1 : undefined}
+        aria-hidden={expanded || undefined}
         aria-label={
           drawerMode
             ? t("sidebar.openPanel", { title })
@@ -197,7 +200,7 @@ export default function SidePanel({
               Module actions live on their own row below so the title always has room. */}
           <div className="flex items-center gap-1.5 px-3 py-2.5 border-b border-border/60 flex-none">
             <IconButton
-              label={pinned ? t("sidebar.unpin") : t("sidebar.pin")}
+              label={pinned ? t("sidebar.unpinNamed", { title }) : t("sidebar.pinNamed", { title })}
               size="sm"
               variant="ghost"
               onClick={onToggleCollapse}
@@ -245,7 +248,7 @@ export default function SidePanel({
             <>
               {pinRoom && (
                 <IconButton
-                  label={t("sidebar.pin")}
+                  label={t("sidebar.pinNamed", { title })}
                   size="sm"
                   variant="ghost"
                   onClick={() => {

frontend/src/i18n/locales/en/sidebar.json

@@ -10,8 +10,6 @@
   "hideWidget": "Hide widget",
   "expand": "Expand",
   "collapse": "Collapse",
-  "pin": "Pin panel open",
-  "unpin": "Unpin panel",
   "pinNamed": "Pin {{title}} open",
   "unpinNamed": "Unpin {{title}}",
   "openPanel": "Open {{title}}",

frontend/src/i18n/locales/hu/sidebar.json

@@ -10,8 +10,6 @@
   "hideWidget": "Modul elrejtése",
   "expand": "Kibontás",
   "collapse": "Összecsukás",
-  "pin": "Panel rögzítése nyitva",
-  "unpin": "Panel rögzítésének feloldása",
   "pinNamed": "{{title}} rögzítése nyitva",
   "unpinNamed": "{{title}} rögzítésének feloldása",
   "openPanel": "{{title}} megnyitása",