chore: merge windows/ into src/ and remove duplicate folder
Cross-platform support lives in src/ via _IS_WINDOWS checks. Merges latest upstream additions from windows/ (OAuth secrets, ANTIGRAVITY_MODELS, changelog v3.10.5) into src/ files, then removes the redundant windows/ folder.
feat: Windows native support — tkinter GUI + cross-platform proxy
- User-Agent: ai-sdk/openai-compatible/1.0.25/codebuff (matches official SDK) - metadata: freebuff_instance_id (not codebuff_instance_id) + client_id field - Session POST: empty body {} (not {model: ...}) - Add Freebuff/FreeBuff preset aliases for backward compat
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