feat(core): Add cwd option and child-process execution for custom working directory; implement signal-forwarding child runner; update docs and bump package version to 1.4.0

readme.md

@@ -67,6 +67,8 @@ await runCli('./myScript.ts');
 
 🎯 **TypeScript Native** - Full TypeScript support with excellent IntelliSense.
 
+🔀 **Custom Working Directory** - Execute scripts with different cwds for parallel multi-project workflows.
+
 ## Why tsrun?
 
 Sometimes you just want to run a TypeScript file without setting up a build pipeline, configuring webpack, or waiting for `tsc` to compile. That's where tsrun shines:
@@ -141,6 +143,35 @@ for (const script of scripts) {
 }
 ```
 
+### Running with Custom Working Directory
+
+Execute TypeScript files with a different working directory using the `cwd` option. This is especially useful for parallel execution across multiple projects:
+
+```typescript
+import { runPath } from '@git.zone/tsrun';
+
+// Run with custom cwd
+await runPath('./build.ts', undefined, { cwd: '/path/to/project-a' });
+
+// Parallel execution with different cwds (safe and isolated)
+await Promise.all([
+  runPath('./deploy.ts', undefined, { cwd: '/projects/frontend' }),
+  runPath('./deploy.ts', undefined, { cwd: '/projects/backend' }),
+  runPath('./deploy.ts', undefined, { cwd: '/projects/api' })
+]);
+```
+
+**How it works:**
+- When `cwd` is provided, the script executes in a **child process** for complete isolation
+- Without `cwd`, execution happens **in-process** (faster, less overhead)
+- Child processes inherit all environment variables and stdio connections
+- Perfect for running the same script across multiple project directories
+
+**Notes:**
+- Output from parallel executions may interleave on the console
+- Each child process runs with its own isolated working directory
+- Exit codes and signals are properly forwarded
+
 ## Package Information
 
 - **npmjs**: [@git.zone/tsrun](https://www.npmjs.com/package/@git.zone/tsrun)