Refactor: migrate cmp/* and srv/* roles into sys-stk/* and sys-svc/* namespaces

- Removed obsolete 'cmp' category, introduced 'stk' category (fa-bars-staggered icon).
- Renamed roles:
  * cmp-db-docker → sys-stk-back-stateful
  * cmp-docker-oauth2 → sys-stk-back-stateless
  * srv-domain-provision → sys-stk-front
  * cmp-db-docker-proxy → sys-stk-full-stateful
  * cmp-docker-proxy → sys-stk-full-stateless
  * cmp-rdbms → sys-svc-rdbms
- Updated all include_role references, vars, templates and README.md files.
- Adjusted run_once comments and variable paths accordingly.
- Updated all web-app roles to use new sys-stk/* and sys-svc/* roles.

Conversation: https://chatgpt.com/share/68b0ba66-09f8-800f-86fc-76c47009d431

roles/web-app-taiga/README.md

@@ -39,7 +39,7 @@ By using this role, teams can set up Taiga in minutes on Arch Linux systems —
     - [taiga-contrib-oidc-auth (official)](https://github.com/taigaio/taiga-contrib-oidc-auth)
 - 📨 **Email Backend:** Supports SMTP and console backends for development.
 - 🔁 **Async & Realtime Events:** Includes RabbitMQ and support for Taiga’s event system.
-- 🌐 **Reverse Proxy Ready:** Integrates with Nginx using the `srv-domain-provision` role.
+- 🌐 **Reverse Proxy Ready:** Integrates with Nginx using the `sys-stk-front` role.
 - 🧩 **Composable Design:** Integrates cleanly with other Infinito.Nexus infrastructure roles.
 
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