fix(security): harden remote pairing PIN persistence (#821)

* fix(security): harden remote pairing PIN persistence

* fix(security): harden pairing PIN persistence

* test(ci): accept Windows line endings in PIN contract

* fix(linux): declare libc for secure PIN opens

---------

Co-authored-by: sim <sim@local>

.github/workflows/ci.yml

@@ -158,6 +158,9 @@ jobs:
       - name: Check Windows UI configuration contract
         run: npm run check:windows-ui-config
 
+      - name: Check PIN persistence security contract
+        run: npm run check:pin-persistence-security
+
       - name: Build frontend (tsc + vite)
         run: npm run build