docs: clarify SQL Server integrated security is unsupported

Integrated security / trusted connection (no credentials in the DSN) is
not supported because DBHub uses the pure-JS tedious driver, which lacks
SSPI/Kerberos. NTLM still requires explicit credentials. Documents this
in the SQL Server DSN tab to address issue #316.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: tianzhou

docs/config/command-line.mdx

@@ -112,6 +112,16 @@ Command-line flags are passed when starting DBHub. These have the highest priori
       # Azure AD authentication (password optional/empty)
       sqlserver://username@localhost:1433/mydb?authentication=azure-active-directory-access-token
       ```
+
+      <Note>
+        Integrated security (a trusted connection using the logged-in
+        Windows user, with no username/password in the DSN) is **not
+        supported**. DBHub uses the pure-JS `tedious` driver, which has no
+        SSPI/Kerberos support. Note that `authentication=ntlm` still
+        requires an explicit username and password in the DSN, so it is not
+        a trusted connection. Use SQL authentication or, for Azure SQL,
+        Azure AD instead.
+      </Note>
     </Tab>
 
     <Tab title="SQLite">