Update all guides (NL + EN) for CodePress 2.5.2 features

- Admin guide: RBAC roles, role-based dashboard, plugin types (content/system)
- CodePress developer guide: plugin types, admin plugin API, SCSS compilation, asset serving
- Theme developer guide: SCSS sole CSS source, css_compiled read-only, guide layout
- Content manager guide: layout selection from theme.json, plugin order in frontmatter
- Both NL and EN updated with identical structure
- 35 files updated

guide/en/theme-developer/thema-structuur.md

@@ -2,20 +2,49 @@
 
 ```
 themes/my-theme/
-├── theme.json              # Theme configuration
-├── base.twig               # Main layout
-├── full_content.twig       # Layout: full-width
-├── left_sidebar.twig       # Layout: left sidebar
-├── right_sidebar.twig      # Layout: right sidebar
-├── custom.twig             # Layout: custom
+├── theme.json              # { title, config.default_template, template: layout→.twig }
+├── base.twig               # Main layout (head, header, nav, breadcrumb, footer)
+├── full_content.twig       # Layout: full width
+├── left_sidebar.twig       # Layout: sidebar on the left
+├── right_sidebar.twig      # Layout: sidebar on the right
+├── custom1.twig            # Layout: custom
+├── guide.twig              # Layout: guide with sidebar (Navigation plugin)
 ├── partials/
 │   ├── header.twig
 │   ├── navigation.twig
 │   └── footer.twig
 └── assets/
-    ├── scss/theme.scss     # SCSS source
-    ├── css/                # CSS files
-    ├── js/theme.js         # JavaScript
-    ├── fonts/              # Fonts
-    └── img/                # Images
+    ├── scss/theme.scss     # SCSS source (the only CSS source)
+    ├── css_compiled/       # Generated by scssphp (read-only, do not edit manually)
+    ├── css/                # External CSS (bootstrap.min.css, bootstrap-icons.css, mobile.css)
+    ├── js/                 # app.js, bootstrap.bundle.min.js
+    ├── fonts/              # bootstrap-icons.woff, woff2
+    └── img/                # favicon, icon, world-map
+```
+
+## SCSS is the only CSS source
+
+- **ALWAYS** edit `assets/scss/theme.scss` — this is the only CSS source
+- `ThemeManager` compiles SCSS at runtime to `assets/css_compiled/theme.css` via scssphp
+- `assets/css_compiled/` is **read-only** — do not edit manually
+- **NEVER** create or edit `assets/css/theme.css` manually; this file must not exist
+- `ThemeManager::getCssUrl()` priority: 1) `assets/css/theme.css` (manual), 2) `assets/css_compiled/theme.css` (compiled). If `theme.css` exists, the SCSS is ignored.
+- After SCSS changes: remove `assets/css_compiled/theme.css` and `.mtime` to force recompilation
+
+```bash
+rm themes/my-theme/assets/css_compiled/theme.css themes/my-theme/assets/css_compiled/.mtime
+```
+
+## guide.twig
+
+Special layout for guides. Injects the Navigation plugin into the sidebar for sidebar navigation. Automatically used for pages in the `guide/` folder.
+
+## Plugin CSS loading
+
+Plugin CSS is automatically loaded after theme CSS in `base.twig`, so themes can override plugin styling:
+
+```twig
+{% for cssUrl in plugin_css_urls|default([]) %}
+    <link href="{{ cssUrl }}" rel="stylesheet">
+{% endfor %}
 ```