mcp: createHandler lacks readonly mode guard

## Description
The \createHandler\ in \pkg/mcp/tools_create.go\ lacks the \s.readonly.Load()\ check that is present in other mutating tools like \deployHandler\ and \deleteHandler\.

Because of this, an MCP client can execute the \create\ command (which writes project scaffolding files to the disk) even when the server is operating in readonly mode.

## Expected Behavior
The \create\ tool should check \s.readonly.Load()\ and return an error if readonly mode is enabled, matching the behavior of \deploy\ and \delete\.