fix: start codex on Windows by using shell; keep mcp args parseable (#40)

Windows global installs expose codex as codex.cmd; spawning 'codex' without shell hits ENOENT.

Enable shell to align with Claude's Windows behavior and resolve PATH lookup.

Shell spawn makes cmd.exe strip TOML double quotes in -c arrays, so args become a string.

Switch mcp args to TOML literal (single-quoted) arrays to preserve types; update tests.

cli/src/codex/codexLocal.ts

@@ -80,7 +80,8 @@ export async function codexLocal(opts: {
             spawnName: 'codex',
             installHint: 'Codex CLI',
             includeCause: true,
-            logExit: true
+            logExit: true,
+            shell: process.platform === 'win32'
         });
     } finally {
         process.stdin.resume();