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)

package.json

@@ -19,7 +19,8 @@
   "scripts": {
     "prepare": "mkdir -p dist/dirigent && cp plugin/* dist/dirigent/",
     "postinstall": "node scripts/install-dirigent-openclaw.mjs --install",
-    "uninstall": "node scripts/install-dirigent-openclaw.mjs --uninstall"
+    "uninstall": "node scripts/install-dirigent-openclaw.mjs --uninstall",
+    "update": "node scripts/install-dirigent-openclaw.mjs --update"
   },
   "keywords": [
     "openclaw",