docs: audit and refresh documentation with updated screenshots (#197)

Update 11 doc pages with accurate content and capture 14 fresh
screenshots. Remove JWT_SECRET from configuration (auto-generated),
fix editor container actions, add missing Settings sections, update
Features Overview, and add remote alerts documentation.

docs/features/webhooks.mdx

@@ -18,6 +18,10 @@ Sencho webhooks let external systems trigger stack actions over HTTP. The typica
 
 ## Creating a webhook
 
+<Frame>
+  <img src="/images/webhooks/webhooks-settings.png" alt="Webhooks settings panel" />
+</Frame>
+
 Open **Settings → Webhooks** and click **Create Webhook**. Fill in:
 
 | Field | Description |