MCP: backslashes need to be escaped when adding server info

### Describe the bug

When adding an MCP server from the CLI, you get a nice TUI to define the info for the server. However, if you put something into "Command" with backslashes (i.e. `dotnet run --project D:\projects\terminal\src\tools\wt.mcp`), the backslashes don't automatically get escaped! This results in the MCP server not working!

When you later check the MCP server configuration, it will remove the `\` so it ends up looking like this: `dotnet run --project D:projectsterminalsrctoolswt.mcp`.

### Affected version

_No response_

### Steps to reproduce the behavior

1. `/mcp`
2. `a` to add a new server
3. fill out the details; in `Command` use something with backslashes (see example above)
4. save

The MCP server fails to work. The error doesn't have anything to do with backslashes either! (which is expected tbh, but it made tracking this down a bit harder)

### Expected behavior

Given that it's a TUI, there should not be a need to escape characters or backslashes.

### Additional context

_No response_