#22812: fix(node-host): auto-create cwd before exec spawn to prevent misleading ENOENT

## Problem When `exec` runs on a node and the agent workspace directory doesn't exist on the remote machine, Node.js throws `spawn /bin/sh ENOENT`. This misleadingly points at the shell binary rather than the real cause: the specified `cwd` directory is missing. This blocks all exec commands on newly registered agent/node pairs until the user manually creates the workspace directory, and the error message sends users on a wild goose chase debugging shell binary paths. ## Fix Add a best-effort `fs.mkdirSync(cwd, { recursive: true })` in `runCommand()` before spawning the child process. The `recursive: true` flag is a no-op if the directory already exists. The try/catch ensures that if mkdir fails (e.g. permission denied), the original spawn error still surfaces. ## Changes - `src/node-host/invoke.ts`: Auto-create `cwd` directory before `spawn()` call Fixes #22793 <!-- greptile_comment --> <h3>Greptile Summary</h3> Auto-creates the working directory (`cwd`) before spawning child processes in `runCommand()` to prevent misleading `ENOENT` errors. When the `cwd` doesn't exist, Node.js previously surfaced the error as "spawn /bin/sh ENOENT", incorrectly pointing at the shell binary instead of the missing directory. The fix uses `fs.mkdirSync(cwd, { recursive: true })` in a try/catch block - if directory creation fails, the original spawn error will still surface, ensuring proper error reporting. <h3>Confidence Score: 5/5</h3> - This PR is safe to merge with minimal risk - The change is minimal, focused, and follows established patterns in the codebase. The fix uses `recursive: true` which is a no-op for existing directories, and the try/catch ensures that failures don't mask underlying issues. The approach matches similar `mkdirSync` patterns used throughout the codebase (found in 100+ locations). No security concerns - the code properly handles errors and doesn't introduce new attack vectors. - No files require special attention _{Last reviewed commit: 2311143} <!-- greptile_other_comments_section --> <!-- /greptile_comment -->