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/admin-beheerder/thema-beheer.md

@@ -2,20 +2,65 @@
 
 ## Managing themes
 
-1. Go to **Theme** in admin menu
-2. **Activate** - Choose active theme
-3. **Compile SCSS** - Process SCSS to CSS
-4. **New theme** - Create custom theme
+1. Go to **Theme** in the admin menu
+2. **Activate** — Choose the active theme (stored in `config.json`)
+3. **Compile SCSS** — Process SCSS to CSS (forced)
+4. **New theme** — Create a custom theme via admin or manually
 
 ## Theme structure
 
 ```
 themes/default/
-├── theme.json          # Theme configuration
-├── base.twig           # Main layout
-├── full_content.twig   # Layouts
-├── left_sidebar.twig
-├── right_sidebar.twig
-├── partials/           # Header, nav, footer
-└── assets/             # CSS, JS, images
-```
+├── 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 (only CSS source — manual css/theme.css must not exist)
+    ├── 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
+```
+
+## theme.json
+
+```json
+{
+    "title": "default",
+    "config": {
+        "default_template": "full_content"
+    },
+    "template": {
+        "full_content": "full_content.twig",
+        "left_sidebar": "left_sidebar.twig",
+        "right_sidebar": "right_sidebar.twig",
+        "custom1": "custom1.twig",
+        "guide": "guide.twig"
+    }
+}
+```
+
+- `title` — Display name in admin
+- `config.default_template` — Default layout for pages without a `layout:` frontmatter
+- `template` — Mapping from layout name to `.twig` file
+
+## SCSS compilation
+
+- `ThemeManager` compiles `assets/scss/theme.scss` at runtime to `assets/css_compiled/theme.css` via scssphp
+- `css_compiled/` is **read-only** — do not edit manually
+- `assets/css/theme.css` must **not** exist; otherwise `ThemeManager::getCssUrl()` ignores the SCSS
+- After SCSS changes: remove `assets/css_compiled/theme.css` and `.mtime` to force recompilation
+
+## Layouts
+
+Layouts are chosen via the frontmatter `layout:` key in content files. Unknown layouts fall back to `config.default_template` from `theme.json`.
+
+## guide.twig
+
+Special layout for guides. Injects the Navigation plugin into the sidebar for sidebar navigation. Automatically used for pages in the `guide/` folder.