fix(mcp): add example to server name validation error message

Fixes bounty issue #1604

The error message for invalid MCP server names now includes an example
('my-server') to help users understand the expected format.

Author: factorydroid

cortex-cli/src/mcp_cmd.rs

@@ -2,8 +2,8 @@
 
 use anyhow::{Context, Result, bail};
 use clap::{ArgGroup, Parser};
-use cortex_common::dirs::get_cortex_home;
 use cortex_common::CliConfigOverrides;
+use cortex_common::dirs::get_cortex_home;
 use std::io::{self, BufRead, Write};
 
 // ============================================================================
@@ -918,7 +918,9 @@ fn validate_server_name(name: &str) -> Result<()> {
         .all(|c| c.is_ascii_alphanumeric() || c == '-' || c == '_');
 
     if !is_valid_chars {
-        bail!("invalid server name '{name}' (use letters, numbers, '-', '_')");
+        bail!(
+            "invalid server name '{name}' (use letters, numbers, '-', '_'); example: 'my-server'"
+        );
     }
 
     // Must start with a letter or underscore