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]>

.github/workflows/ci.yml

@@ -82,6 +82,7 @@ jobs:
       - run: pnpm typecheck
       - run: pnpm lint
       - run: pnpm format:check
+      - run: pnpm knip
       - run: pnpm test
       - run: pnpm build