fix(a11y): names that carry what they show; the unused-key check stops covering whole files

- The palette launcher's name replaced its visible "Jump to…" (and the key cap's its "Ctrl K"):
  a voice-control "click Jump to" matched nothing (WCAG 2.5.3). Each name contains its text now.
- SegmentedToggle's `title` was only a tooltip on a non-focusable box — the live search's "how
  many per batch" hint reached no keyboard or screen-reader user. It is the group's accessible
  description, standalone and captioned alike.
- The unused-key contract let a template like `card.${status}` cover its whole namespace, which hid
  five dead keys (deleted). Dynamic keys are matched by shape (`editor.*.hint`); a bare namespace
  shape covers nothing, and the audit/quota namespaces are now held both ways by backendIds.
- CLAUDE.md's "FE control" row matches the lint rule it cites; each no-restricted-syntax entry has
  its reason directly above it.

frontend/src/components/ui/SegmentedToggle.dom.test.tsx

@@ -69,4 +69,39 @@ describe("SegmentedToggle", () => {
     expect(screen.getByTestId("ic-my")).toBeTruthy();
     expect(screen.getByRole("button", { name: "Mine" }).getAttribute("title")).toBe("Your subs");
   });
+
+  // The hint was a `title` on a non-focusable box: the pointer's tooltip, and nothing at all for a
+  // keyboard or screen-reader user (deep review, debt burn). It is the group's description now.
+  it("describes the group by its title, standalone and captioned alike", () => {
+    render(
+      <>
+        <SegmentedToggle
+          options={OPTS}
+          value="or"
+          onChange={vi.fn()}
+          ariaLabel="Show"
+          title="Results per batch"
+        />
+        <SegmentedToggle
+          options={OPTS}
+          value="or"
+          onChange={vi.fn()}
+          ariaLabel="Match"
+          label="Match"
+          title="Any or all"
+        />
+      </>,
+    );
+    expect(
+      screen.getByRole("group", { name: "Show", description: "Results per batch" }),
+    ).toBeTruthy();
+    expect(screen.getByRole("group", { name: "Match", description: "Any or all" })).toBeTruthy();
+  });
+
+  it("adds no description without a title", () => {
+    render(<SegmentedToggle options={OPTS} value="or" onChange={vi.fn()} ariaLabel="Match" />);
+    expect(screen.getByRole("group", { name: "Match" }).hasAttribute("aria-describedby")).toBe(
+      false,
+    );
+  });
 });

frontend/src/components/ui/SegmentedToggle.tsx

@@ -1,4 +1,4 @@
-import { type ReactNode } from "react";
+import { useId, type ReactNode } from "react";
 
 // Shared MATCH / segmented primitive — a rounded-full pill track where exactly ONE option is active
 // (radio-like). Backs the feed any/all + or/and "Match" toggles and the feed Mine/Library scope bar,
@@ -31,13 +31,17 @@ export default function SegmentedToggle<T extends string>({
   // Optional left-hand caption; when set the control renders as a justify-between row (the feed/Plex
   // "Match" toggles). Omit for a standalone bar (the Mine/Library scope switch).
   label?: ReactNode;
-  title?: string; // tooltip on the whole row (caption mode only)
+  // What the choice means, beyond its name: the row's tooltip for the pointer, and the group's
+  // accessible description for the keyboard and a screen reader — a `title` on a non-focusable box
+  // alone reaches neither (it had only ever been the pointer's).
+  title?: string;
   // Full-width track with flex-1 buttons (the scope bar); default is intrinsic width.
   fullWidth?: boolean;
   // sm = text-3xs, compact padding (the captioned match toggles); md = text-xs (the scope bar).
   size?: "sm" | "md";
   className?: string;
 }) {
+  const hintId = useId();
   const track = (
     <div
       className={`inline-flex items-center rounded-full border border-border bg-card p-0.5 ${
@@ -45,7 +49,14 @@ export default function SegmentedToggle<T extends string>({
       }${fullWidth ? " w-full" : ""}`}
       role="group"
       aria-label={ariaLabel}
+      aria-describedby={title ? hintId : undefined}
+      title={label == null ? title : undefined}
     >
+      {title && (
+        <span id={hintId} hidden>
+          {title}
+        </span>
+      )}
       {options.map((o) => (
         <button
           key={o.value}