chore(deps): bump @socketsecurity/lib-stable to 5.21.0

Picks up the 5.21.0 release published in the prior commit:
- `.claude/hooks/check-new-deps` — 5.19.1 → 5.21.0
- root `@socketsecurity/lib-stable` alias — 5.20.1 → 5.21.0

Lockfile regenerated via `pnpm run update` + `pnpm i`.

Author: jdalton

.claude/hooks/check-new-deps/package.json

@@ -11,7 +11,7 @@
   },
   "dependencies": {
     "@socketregistry/packageurl-js": "1.4.2",
-    "@socketsecurity/lib": "5.19.1",
+    "@socketsecurity/lib": "5.21.0",
     "@socketsecurity/sdk": "4.0.1"
   },
   "devDependencies": {

package.json

@@ -724,7 +724,7 @@
     "@socketregistry/is-unicode-supported": "1.0.5",
     "@socketregistry/packageurl-js": "1.4.2",
     "@socketregistry/yocto-spinner": "1.0.25",
-    "@socketsecurity/lib-stable": "npm:@socketsecurity/lib@5.20.1",
+    "@socketsecurity/lib-stable": "npm:@socketsecurity/lib@5.21.0",
     "@types/node": "24.9.2",
     "@typescript/native-preview": "7.0.0-dev.20260415.1",
     "@vitest/coverage-v8": "4.0.3",