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,
+    );
+  });
 });