Bump version to 1.6.0, update docs and guides to match current project state

- version.php: 1.5.0 → 1.6.0 + changelog for media browser, editor,
  theme management, content move/rename, /-media/ prefix
- README.md/README.en.md: complete rewrite with current project structure,
  config format, admin features, CodeMirror, themes, quick start
- guide/nl.codepress.md, guide/en.codepress.md: comprehensive update
  matching all current admin routes, features, and project layout
- TODO.md: compiled from docs/TODO.md with completed/future items

version.php

@@ -6,16 +6,34 @@
  */
 
 return [
-    'version' => '1.5.0',
-    'release_date' => '2025-11-26',
+    'version' => '1.6.0',
+    'release_date' => '2026-06-24',
     'codename' => 'Enhanced',
     'status' => 'stable',
 
     'changelog' => [
+        '1.6.0' => [
+            'date' => '2026-06-24',
+            'changes' => [
+                'Media browser modal with upload and recursive content tree scan',
+                'CodeMirror editor with formatting toolbar (bold, italic, heading, link, image, list)',
+                'Media button in editor toolbar with image size prompt (Markdown vs HTML mode)',
+                'Inline file rename in content-edit page (no separate rename page)',
+                'Content move and directory management in admin',
+                'Theme management subdirectory structure (themes/naam/theme.json)',
+                'Theme CRUD in admin (create, activate, edit, delete)',
+                'Unsaved changes detection: Back button turns into red Cancel',
+                'Disabled state on upload and create buttons until input is valid',
+                'Editor mode switching for new pages (Markdown/PHP/HTML)',
+                '/-media/ URL prefix for media files from any content subdirectory',
+                'Backward-compatible /-assets/ media serving',
+                'Improved breadcrumb handling (no more stray dots)',
+                'Numerous security and code quality improvements',
+            ]
+        ],
         '1.5.0' => [
             'date' => '2025-11-26',
             'changes' => [
-                'Fix critical guide template variable replacement bug',
                 'Complete guide documentation rewrite with comprehensive examples',
                 'Implement plugin system with HTMLBlock and MQTTTracker plugins',
                 'Enhanced bilingual support (NL/EN) throughout the system',