feat(frontend): Kinetic Precision design system — new lime theme, glassmorphism, redesigned pages

- New design system: Stitch (kinetic-precision.css) with lime (#cafd00) accent
- New Google Fonts: Lexend, Plus Jakarta Sans, Space Grotesk
- New page: BenchmarksPage with strength/endurance/body tracking
- Redesigned: Dashboard, ProgressPage, WorkoutPage, LoginPage + LoginPage.css
- Add shared glassmorphism nav, kinetic buttons, intensity indicators
- Build: 265KB JS / 88KB CSS / 2.54s (clean)

scripts/preflight/05-rollback-safety.sh

@@ -0,0 +1,15 @@
+#!/bin/bash
+# Rollback Safety Verification
+NAMESPACE="gravl-prod"
+STAGING_NS="gravl-staging"
+
+echo "=== Rollback Safety Checks ==="
+echo ""
+echo "Staging environment status (rollback target):"
+kubectl get deployment -n "$STAGING_NS" -o wide
+echo ""
+echo "Staging service health:"
+kubectl get svc -n "$STAGING_NS" -o wide
+echo ""
+echo "Deployment revision history:"
+kubectl rollout history deployment --all-namespaces | grep gravl || echo "No rollout history yet"