feat(process): support env overrides in exec

src/process/exec.ts

@@ -47,6 +47,7 @@ export type CommandOptions = {
   timeoutMs: number;
   cwd?: string;
   input?: string;
+  env?: NodeJS.ProcessEnv;
 };
 
 export async function runCommandWithTimeout(
@@ -57,13 +58,14 @@ export async function runCommandWithTimeout(
     typeof optionsOrTimeout === "number"
       ? { timeoutMs: optionsOrTimeout }
       : optionsOrTimeout;
-  const { timeoutMs, cwd, input } = options;
+  const { timeoutMs, cwd, input, env } = options;
 
   // Spawn with inherited stdin (TTY) so tools like `pi` stay interactive when needed.
   return await new Promise((resolve, reject) => {
     const child = spawn(argv[0], argv.slice(1), {
       stdio: [input ? "pipe" : "inherit", "pipe", "pipe"],
       cwd,
+      env: env ? { ...process.env, ...env } : process.env,
     });
     let stdout = "";
     let stderr = "";