Fix worktree setup scripts losing PATH (#1908)

* fix(worktree): preserve PATH for lifecycle scripts

Lifecycle command strings were running through login shells, which could rewrite PATH before setup commands saw the daemon environment. Use the shared stable script-shell helper without login startup files, and route related project-authored command strings through it.

* fix(worktree): ignore Bash startup env hook

Project command strings should not source shell startup hooks before they see Paseo's supplied environment. Strip BASH_ENV from lifecycle, loop verify, and ACP string-command shells and pin the behavior in setup tests.

* fix(worktree): resolve Bash through PATH

* fix(worktree): preserve Windows cmd command strings

* test(acp): expect Windows cmd terminal strings

packages/server/src/utils/string-command-shell.ts

@@ -1,6 +1,7 @@
 export interface BuildStringCommandShellInvocationOptions {
   command: string;
   platform?: NodeJS.Platform;
+  windowsShell?: "powershell" | "cmd";
 }
 
 export interface StringCommandShellInvocation {
@@ -8,12 +9,31 @@ export interface StringCommandShellInvocation {
   args: string[];
 }
 
+export function createStringCommandShellEnv(env: NodeJS.ProcessEnv): NodeJS.ProcessEnv {
+  const sanitized = { ...env };
+  delete sanitized.BASH_ENV;
+  return sanitized;
+}
+
+export function createStringCommandShellEnvOverlay(): Record<string, string | undefined> {
+  return { BASH_ENV: undefined };
+}
+
 export function buildStringCommandShellInvocation(
   options: BuildStringCommandShellInvocationOptions,
 ): StringCommandShellInvocation {
   const platform = options.platform ?? process.platform;
 
+  // Project-authored command strings use a stable script shell. The caller supplies
+  // the environment; shell startup files should not rewrite it behind our back.
   if (platform === "win32") {
+    if (options.windowsShell === "cmd") {
+      return {
+        shell: "cmd.exe",
+        args: ["/c", options.command],
+      };
+    }
+
     return {
       shell: "powershell",
       args: [
@@ -28,7 +48,7 @@ export function buildStringCommandShellInvocation(
   }
 
   return {
-    shell: "/bin/bash",
-    args: ["-lc", options.command],
+    shell: "bash",
+    args: ["-c", options.command],
   };
 }