docs: update screenshot

Author: tianzhou

docs/images/workbench/custom-tool.webp

@@ -5,6 +5,8 @@ description: "View recent tool execution history"
 
 The Request History page (`/requests`) displays recent tool executions, helping you track queries and debug issues.
 
+![request-history](https://raw.githubusercontent.com/bytebase/dbhub/main/docs/images/workbench/request-history.webp)
+
 ## Data Retention
 
 Request history is stored in memory (resets on restart), keeping the latest 100 requests per source.

docs/images/workbench/execute-sql.webp

@@ -9,6 +9,8 @@ Run pre-defined SQL statements through a constrained form interface, with URL qu
 
 For `execute_sql` tools, you get a full SQL editor with syntax highlighting.
 
+![execute-sql](https://raw.githubusercontent.com/bytebase/dbhub/main/docs/images/workbench/execute-sql.webp)
+
 | Parameter | Description | Example |
 |-----------|-------------|---------|
 | `sql` | Prefills the SQL editor (URL encoded) | `?sql=SELECT%20*%20FROM%20users%20LIMIT%2010` |