Add Valkey infrastructure role as Redis-compatible cache service

- Implemented complete Valkey infrastructure role following PostgreSQL patterns
- Provides 100% Redis-compatible high-performance data structure store
- Configured for multi-application support with database isolation
- Security-focused: localhost-only binding, password auth, systemd hardening
- Arch Linux compatible: uses native Valkey package with Redis compatibility
- Database allocation strategy: DB 0 reserved, DB 1+ for applications
- Full systemd integration with security overrides and proper service management
- Redis client compatibility maintained for seamless application integration
- Ready for Authentik and future container workloads requiring cache services

roles/valkey/handlers/main.yml

@@ -0,0 +1,17 @@
+---
+# Valkey Infrastructure Role - Handlers
+# Matches the handler pattern from PostgreSQL role
+
+- name: reload systemd
+  systemd:
+    daemon_reload: yes
+
+- name: restart valkey
+  systemd:
+    name: valkey
+    state: restarted
+
+- name: reload valkey
+  systemd:
+    name: valkey
+    state: reloaded