fix(codex): prefer cmd wrappers over powershell on windows

- keep Windows Codex detection on the npm cmd shim when available

- add regression tests for cmd-first and ps1-to-cmd fallback selection

src/targets/codex-detector.ts

@@ -10,17 +10,26 @@ const CODEX_CONFIG_OVERRIDE_PROBE_ARGS = ['-c', 'model="gpt-5"', '--version'];
 function buildWindowsCodexCandidates(matches: string[]): string[] {
   const shellCandidates = matches.filter((entry) => /\.(exe|cmd|bat|ps1)$/i.test(entry));
   const bareCandidates = matches.filter((entry) => !/\.(exe|cmd|bat|ps1)$/i.test(entry));
-  const prioritized: string[] = [];
-
-  for (const entry of shellCandidates) {
-    if (/\.(cmd|bat)$/i.test(entry)) {
-      prioritized.push(entry.replace(/\.(cmd|bat)$/i, '.ps1'));
+  const prioritized = shellCandidates.map((entry) => {
+    if (!/\.ps1$/i.test(entry)) {
+      return entry;
     }
-    prioritized.push(entry);
-  }
 
-  prioritized.push(...bareCandidates);
-  return [...new Set(prioritized)];
+    for (const preferredExtension of ['.cmd', '.bat', '.exe']) {
+      const siblingCandidate = entry.replace(/\.ps1$/i, preferredExtension);
+      try {
+        if (fs.statSync(siblingCandidate).isFile()) {
+          return siblingCandidate;
+        }
+      } catch {
+        // Ignore missing sibling wrappers and keep the original PowerShell path.
+      }
+    }
+
+    return entry;
+  });
+
+  return [...new Set([...prioritized, ...bareCandidates])];
 }
 
 function runCodexProbe(codexPath: string, args: string[]): string | undefined {