feat: Windows native support — tkinter GUI, cross-platform proxy

Based on v3.10.4 upstream.

New files:
- src/codex-launcher-gui.py: full tkinter GUI (10 classes) replacing GTK on Windows
- src/codex_launcher_lib.py: shared cross-platform module (~1870 lines)
- src/cleanup-codex-stale.py: cross-platform process cleanup

translate-proxy.py Windows adaptations:
- Platform-aware paths: %LOCALAPPDATA% for cache, %APPDATA% for config
- Platform-aware credentials, signals, memory reporting, shell commands
- UTF-8 encoding on all file writes (Windows cp1252 default)
- FORCE_MODEL: proxy overrides Codex Desktop model selection
- DeepSeek reasoning_content round-trip for multi-turn tool sessions
- Cleanup orphan .tmp files at startup
- requests.log rotation (2000 lines cap)
- User-Agent: codex-launcher/1.0 in outbound HTTP requests

src/cleanup-codex-stale.py

@@ -0,0 +1,101 @@
+#!/usr/bin/env python3
+"""Cleanup stale Codex Launcher processes and artifacts — cross-platform.
+
+Kills registered process groups and removes stale PID/socket files left
+by previous Codex Launcher sessions.
+
+Windows: uses taskkill /F /T /PID
+Linux: uses kill -TERM -- -PGID
+"""
+
+import json, os, sys, subprocess, time
+from pathlib import Path
+
+IS_WINDOWS = sys.platform == "win32"
+
+if IS_WINDOWS:
+    _local = os.environ.get("LOCALAPPDATA", str(Path.home() / "AppData" / "Local"))
+    PID_REGISTRY = Path(_local) / "codex-launcher" / "pids.json"
+    CODEX_DIR = Path.home() / ".codex"
+    _local_share = Path(_local)
+    _cache = Path(_local)
+else:
+    PID_REGISTRY = Path.home() / ".cache" / "codex-launcher" / "pids.json"
+    CODEX_DIR = Path.home() / ".codex"
+    _local_share = Path.home() / ".local" / "share"
+    _cache = Path.home() / ".cache"
+
+
+def kill_group(pid):
+    if IS_WINDOWS:
+        subprocess.run(["taskkill", "/F", "/T", "/PID", str(pid)],
+                       capture_output=True, timeout=10)
+    else:
+        import signal
+        try:
+            pgid = os.getpgid(pid)
+            os.killpg(pgid, signal.SIGTERM)
+            time.sleep(0.5)
+            try:
+                os.killpg(pgid, signal.SIGKILL)
+            except OSError:
+                pass
+        except OSError:
+            pass
+
+
+def main():
+    print("[cleanup] Cleaning up stale Codex Launcher processes...", file=sys.stderr)
+
+    if PID_REGISTRY.exists():
+        try:
+            with open(PID_REGISTRY) as f:
+                registry = json.load(f)
+        except Exception as e:
+            print(f"[cleanup] Failed to read PID registry: {e}", file=sys.stderr)
+            registry = {}
+
+        for kind, info in registry.items():
+            pid = info.get("pid") if isinstance(info, dict) else info
+            if pid and isinstance(pid, int):
+                print(f"[cleanup] Killing {kind} (PID {pid})", file=sys.stderr)
+                kill_group(pid)
+
+        try:
+            PID_REGISTRY.unlink()
+        except OSError:
+            pass
+    else:
+        print("[cleanup] No PID registry found — nothing to stop", file=sys.stderr)
+
+    stale_files = []
+    if IS_WINDOWS:
+        stale_files = [
+            _cache / "codex-desktop" / ".codex-desktop-pid",
+            _cache / "codex-desktop" / ".webview-pid",
+        ]
+    else:
+        stale_files = [
+            CODEX_DIR / ".launch-action-socket",
+            CODEX_DIR / ".codex-desktop-launch-action",
+            CODEX_DIR / ".codex-desktop-pid",
+            CODEX_DIR / ".webview-pid",
+            _local_share / "codex-desktop" / ".codex-desktop-pid",
+            _local_share / "codex-desktop" / ".webview-pid",
+            _cache / "codex-desktop" / ".codex-desktop-pid",
+            _cache / "codex-desktop" / ".webview-pid",
+        ]
+
+    for fp in stale_files:
+        try:
+            if fp.exists():
+                fp.unlink()
+                print(f"[cleanup] Removed {fp}", file=sys.stderr)
+        except OSError:
+            pass
+
+    print("[cleanup] Done", file=sys.stderr)
+
+
+if __name__ == "__main__":
+    main()