docs: expand Docusaurus coverage across CLI, tools, skills, and skins (#1232)

- add code-derived reference pages for slash commands, tools, toolsets,
  bundled skills, and official optional skills
- document the skin system and link visual theming separately from
  conversational personality
- refresh quickstart, configuration, environment variable, and messaging
  docs to match current provider, gateway, and browser behavior
- fix stale command, session, and Home Assistant configuration guidance

website/sidebars.ts

@@ -54,6 +54,7 @@ const sidebars: SidebarsConfig = {
             'user-guide/features/memory',
             'user-guide/features/context-files',
             'user-guide/features/personality',
+            'user-guide/features/skins',
           ],
         },
         {
@@ -111,6 +112,11 @@ const sidebars: SidebarsConfig = {
       label: 'Reference',
       items: [
         'reference/cli-commands',
+        'reference/slash-commands',
+        'reference/tools-reference',
+        'reference/toolsets-reference',
+        'reference/skills-catalog',
+        'reference/optional-skills-catalog',
         'reference/environment-variables',
         'reference/faq',
       ],