fix: remove any types, dead code, unused exports; add comprehensive tests

- Fix handleRotate bug ignoring Result from rotateSealedSecret()
- Fix dead code branch in useControllerHealth
- Replace all `any` types with `unknown` + type guards
- Delete unused functions/exports (452 lines removed)
- Add 18 new test files covering all hooks, libs, and components
- 233 tests passing, zero tsc errors, zero lint issues

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/components/LoadingSkeletons.tsx

@@ -116,22 +116,6 @@ export function SealingKeysListSkeleton() {
   );
 }
 
-/**
- * Skeleton for certificate information
- *
- * Shows placeholder for certificate metadata
- */
-export function CertificateInfoSkeleton() {
-  return (
-    <Box>
-      <Skeleton variant="text" width="60%" animation="wave" />
-      <Skeleton variant="text" width="40%" animation="wave" />
-      <Skeleton variant="text" width="50%" animation="wave" />
-      <Skeleton variant="text" width="45%" animation="wave" />
-    </Box>
-  );
-}
-
 /**
  * Skeleton for controller health status
  *