Add hardened .npmrc for supply-chain security

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: karanshah-browserstack

.npmrc

@@ -0,0 +1,7 @@
+# Supply-chain hardening directives
+ignore-scripts=true
+strict-ssl=true
+save-exact=true
+# engine-strict=true  # disabled: hard-fails `npm ci` on Node 18.20.7 — the repo overrides field pins serialize-javascript@7.0.5 (engines node>=20.0.0), which breaks Cypress-14-supported Node 18. Re-enable only after the serialize-javascript override is constrained to a Node-18-compatible line or Node 18 is officially dropped.
+legacy-peer-deps=false
+audit-level=high