chore: add knip and remove the dead code it reports (#247)

Adds knip (pnpm knip, knip.ts covering src, scripts, perf and e2e) and runs it in the CI frontend job. Removes what it reported: the unused codemirror and @types/dompurify dependencies, exports and test hooks used nowhere (AppLogo, Tooltip, barrel re-exports, duplicate default exports of lazily loaded settings pages), the unused iterateAll helper, and the zh entry for a deleted notification. rustfmt (used by lint-staged) is ignored as a toolchain binary.

Co-authored-by: jaw52 <[email protected]>

src/features/plugins/PluginsPage.tsx

@@ -678,5 +678,3 @@ export function PluginsPage() {
     </div>
   );
 }
-
-export default PluginsPage;

src/features/plugins/store.ts

@@ -183,6 +183,3 @@ export async function runPluginCommand(pluginId: string, commandId: string, arg:
     return null;
   }
 }
-
-/** Plugins whose contributions are live (enabled and running, or contribution-only). */
-export const isLive = (p: PluginInfo) => p.status === "active" || p.status === "static";