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/docs/user-guide/features/skins.md

@@ -0,0 +1,81 @@
+---
+sidebar_position: 10
+title: "Skins & Themes"
+description: "Customize the Hermes CLI with built-in and user-defined skins"
+---
+
+# Skins & Themes
+
+Skins control the **visual presentation** of the Hermes CLI: banner colors, spinner faces and verbs, response-box labels, branding text, and the tool activity prefix.
+
+Conversational style and visual style are separate concepts:
+
+- **Personality** changes the agent's tone and wording.
+- **Skin** changes the CLI's appearance.
+
+## Change skins
+
+```bash
+/skin                # show the current skin and list available skins
+/skin ares           # switch to a built-in skin
+/skin mytheme        # switch to a custom skin from ~/.hermes/skins/mytheme.yaml
+```
+
+Or set the default skin in `~/.hermes/config.yaml`:
+
+```yaml
+display:
+  skin: default
+```
+
+## Built-in skins
+
+| Skin | Description | Agent branding |
+|------|-------------|----------------|
+| `default` | Classic Hermes — gold and kawaii | `Hermes Agent` |
+| `ares` | War-god theme — crimson and bronze | `Ares Agent` |
+| `mono` | Monochrome — clean grayscale | `Hermes Agent` |
+| `slate` | Cool blue — developer-focused | `Hermes Agent` |
+| `poseidon` | Ocean-god theme — deep blue and seafoam | `Poseidon Agent` |
+| `sisyphus` | Sisyphean theme — austere grayscale with persistence | `Sisyphus Agent` |
+| `charizard` | Volcanic theme — burnt orange and ember | `Charizard Agent` |
+
+## What a skin can customize
+
+| Area | Keys |
+|------|------|
+| Banner + response colors | `colors.banner_*`, `colors.response_border` |
+| Spinner animation | `spinner.waiting_faces`, `spinner.thinking_faces`, `spinner.thinking_verbs`, `spinner.wings` |
+| Branding text | `branding.agent_name`, `branding.welcome`, `branding.response_label`, `branding.prompt_symbol` |
+| Tool activity prefix | `tool_prefix` |
+
+## Custom skins
+
+Create YAML files under `~/.hermes/skins/`. User skins inherit missing values from the built-in `default` skin.
+
+```yaml
+name: cyberpunk
+description: Neon terminal theme
+
+colors:
+  banner_border: "#FF00FF"
+  banner_title: "#00FFFF"
+  banner_accent: "#FF1493"
+
+spinner:
+  thinking_verbs: ["jacking in", "decrypting", "uploading"]
+  wings:
+    - ["⟨⚡", "⚡⟩"]
+
+branding:
+  agent_name: "Cyber Agent"
+  response_label: " ⚡ Cyber "
+
+tool_prefix: "▏"
+```
+
+## Operational notes
+
+- Built-in skins load from `hermes_cli/skin_engine.py`.
+- Unknown skins automatically fall back to `default`.
+- `/skin` updates the active CLI theme immediately for the current session.