fix(ci): require clean probe exit for Windows shell/bash detection; add pyyaml dev dep

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

scripts/hooks/plugin-hook-bootstrap.js

@@ -97,7 +97,10 @@ function findShellBinary() {
       windowsHide: true,
       timeout: 30000,
     });
-    if (!probe.error) {
+    // A candidate is only usable if it both spawns AND exits cleanly. The
+    // Windows System32 bash.exe WSL launcher spawns without error but exits
+    // non-zero when no distro is installed, so !probe.error alone is not enough.
+    if (!probe.error && probe.status === 0) {
       _cachedShell = candidate;
       return _cachedShell;
     }
@@ -118,7 +121,9 @@ function findBashBinary() {
 
   for (const candidate of candidates) {
     const probe = spawnSync(candidate, ['-c', ':'], { stdio: 'ignore', windowsHide: true, timeout: 30000 });
-    if (!probe.error) {
+    // Require a clean exit, not just a successful spawn: the Windows System32
+    // bash.exe WSL stub spawns fine but exits non-zero with no distro installed.
+    if (!probe.error && probe.status === 0) {
       _cachedBash = candidate;
       return _cachedBash;
     }