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/i18n/backendIds.contract.test.ts

@@ -201,6 +201,14 @@ describe("backend ids have their names in both languages", () => {
     it(`${lang}: every audit and quota action`, () => {
       expect(auditActions.filter((a) => !idsUnder(keys, "auditActions").has(a))).toEqual([]);
       expect(quotaActions.filter((a) => !idsUnder(keys, "quotaActions").has(a))).toEqual([]);
+      // …and no name for an action the backend no longer has (the unused-key contract leaves
+      // these two namespaces to this check).
+      expect([...idsUnder(keys, "auditActions")].filter((a) => !auditActions.includes(a))).toEqual(
+        [],
+      );
+      expect([...idsUnder(keys, "quotaActions")].filter((a) => !quotaActions.includes(a))).toEqual(
+        [],
+      );
     });
 
     it(`${lang}: every download failure-catalog entry`, () => {