feat(auth): add custom Keycloak login theme matching dashboard

Branded Keycloak login page with CERTifAI dark theme: indigo/teal
color palette, Inter + Space Grotesk fonts, animated background
gradients, card glow, logo float, and button shimmer effects.
Overrides PatternFly v4 defaults including autofill color fix.

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

docker-compose.yml

@@ -15,6 +15,7 @@ services:
       - --import-realm
     volumes:
       - ./keycloak/realm-export.json:/opt/keycloak/data/import/realm-export.json:ro
+      - ./keycloak/themes/certifai:/opt/keycloak/themes/certifai:ro
     healthcheck:
       test: ["CMD", "curl", "-f", "http://localhost:8080/health/ready"]
       interval: 10s