feat(frontend): rename inj roles to sys-front-*, add sys-svc-cdn, cache-busting lookup

Introduce sys-svc-cdn (cdn_paths/cdn_urls/cdn_dirs) and ensure CDN directories + latest symlink.

Rename sys-srv-web-inj-* → sys-front-inj-*; update includes/templates; serve shared/per-app CSS & JS via CDN.

Add lookup_plugins/local_mtime_qs.py for mtime-based cache busting; split CSS into default.css/bootstrap.css + optional per-app style.css.

CSP: use style-src-elem; drop unsafe-inline for styles. Services: fix SYS_SERVICE_ALL_ENABLED bool and controlled flush.

BREAKING CHANGE: role names changed; replace includes and references accordingly.

Conversation: https://chatgpt.com/share/68b55494-9ec4-800f-b559-44707029141d

roles/sys-front-inj-all/README.md

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+# Nginx Global Matomo & Theming Modifier Role 🚀
+
+This role enhances your Nginx configuration by conditionally injecting global Matomo tracking and theming elements into your HTML responses. It uses Nginx sub-filters to seamlessly add tracking scripts and CSS links to your web pages.
+
+---
+
+## Features
+
+- **Global Matomo Tracking**  
+  The role includes Matomo tracking configuration and injects the corresponding tracking script into your HTML.
+
+- **Global Theming**  
+  The role injects a global CSS link for consistent theming across your site.
+
+- **Smart Injection**  
+  Uses Nginx's `sub_filter` to insert the tracking and theming snippets right before the closing `</head>` tag of your HTML documents.
+
+
+This will automatically activate Matomo tracking and/or global theming based on your configuration.
+
+---
+
+## Author
+
+Developed by [Kevin Veen-Birkenbach](https://www.veen.world) 😎
+
+---
+
+Happy automating! 🎉