docs: fill documentation gaps from recent PRs (#2183)

- slash-commands.md: add /approve, /deny (gateway-only), /statusbar
  (CLI-only); update Notes section with new platform-specific commands
- messaging/index.md: add Webhooks to architecture diagram, platform
  toolsets table, and Next Steps links; add /approve and /deny to
  Chat Commands table
- environment-variables.md: add HONCHO_BASE_URL for self-hosted
  Honcho instances
- configuration.md: add Context Pressure Warnings section (separate
  from iteration budget pressure); add base_url to OpenAI TTS config;
  add display.show_cost to Display Settings
- tts.md: add base_url to OpenAI TTS config example

Co-authored-by: Test <test@test.com>

website/docs/user-guide/messaging/index.md

@@ -1,7 +1,7 @@
 ---
 sidebar_position: 1
 title: "Messaging Gateway"
-description: "Chat with Hermes from Telegram, Discord, Slack, WhatsApp, Signal, SMS, Email, Home Assistant, Mattermost, Matrix, DingTalk, or any OpenAI-compatible frontend via the API server — architecture and setup overview"
+description: "Chat with Hermes from Telegram, Discord, Slack, WhatsApp, Signal, SMS, Email, Home Assistant, Mattermost, Matrix, DingTalk, Webhooks, or any OpenAI-compatible frontend via the API server — architecture and setup overview"
 ---
 
 # Messaging Gateway
@@ -28,6 +28,7 @@ flowchart TB
             mx[Matrix]
             dt[DingTalk]
             api["API Server<br/>(OpenAI-compatible)"]
+            wh[Webhooks]
         end
 
         store["Session store<br/>per chat"]
@@ -47,6 +48,7 @@ flowchart TB
     mx --> store
     dt --> store
     api --> store
+    wh --> store
     store --> agent
     cron --> store
 ```
@@ -88,6 +90,8 @@ hermes gateway status --system         # Linux only: inspect the system service
 | `/undo` | Remove the last exchange |
 | `/status` | Show session info |
 | `/stop` | Stop the running agent |
+| `/approve` | Approve a pending dangerous command |
+| `/deny` | Reject a pending dangerous command |
 | `/sethome` | Set this chat as the home channel |
 | `/compress` | Manually compress conversation context |
 | `/title [name]` | Set or show the session title |
@@ -309,6 +313,7 @@ Each platform has its own toolset:
 | Matrix | `hermes-matrix` | Full tools including terminal |
 | DingTalk | `hermes-dingtalk` | Full tools including terminal |
 | API Server | `hermes` (default) | Full tools including terminal |
+| Webhooks | `hermes-webhook` | Full tools including terminal |
 
 ## Next Steps
 
@@ -324,3 +329,4 @@ Each platform has its own toolset:
 - [Matrix Setup](matrix.md)
 - [DingTalk Setup](dingtalk.md)
 - [Open WebUI + API Server](open-webui.md)
+- [Webhooks](webhooks.md)