feat(codex): add Windows support and compatibility for Codex plugin

plugins/codex/README.md

@@ -21,6 +21,7 @@ rules. The shared runner remains a plain shell entrypoint that the skill calls.
 
 ## Install
 
+On Linux/macOS:
 ```bash
 git clone <repo-url> SkillOpt-Sleep
 cd SkillOpt-Sleep
@@ -28,6 +29,14 @@ bash plugins/codex/install.sh          # installs the skill
 export SKILLOPT_SLEEP_REPO="$(pwd)"    # so the runner is found from anywhere
 ```
 
+On Windows (PowerShell):
+```powershell
+git clone <repo-url> SkillOpt-Sleep
+cd SkillOpt-Sleep
+powershell -File plugins/codex/install.ps1
+[System.Environment]::SetEnvironmentVariable("SKILLOPT_SLEEP_REPO", "$(pwd)", "User")
+```
+
 If a previous install created `~/.codex/prompts/sleep.md`, the installer moves
 that deprecated prompt aside with a `.skillopt-legacy*.bak` suffix.