refactor: remove turn tools, rename discord tools, rewrite installer
- Remove turn management tools (turn-status/advance/reset) — internal only,
accessible via /dirigent slash commands
- Rename discord tools: dirigent_discord_channel_create,
dirigent_discord_channel_update, dirigent_discord_member_list
- Rewrite install script:
- Dynamic OpenClaw dir resolution (OPENCLAW_DIR env → openclaw CLI → ~/.openclaw)
- Plugin installed to $(openclaw_dir)/plugins/dirigent
- New --update mode: git pull from latest branch + reinstall
- Cleaner uninstall: removes installed plugin files
- Update docs (FEAT.md, README.md, CHANGELOG.md, TASKLIST.md)