feat: add project-hygiene plugin

Post-task cleanup hook that runs after Claude completes work:
- Deletes temp files (*.tmp, *.bak, __pycache__, etc.)
- Warns about unexpected files in project root
- Identifies orphaned files (test_*, debug_*, *_backup.*)
- Logs actions to .dev/logs/
- Supports project-local config via .hygiene.json

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

project-hygiene/hooks/hooks.json

@@ -0,0 +1,9 @@
+{
+  "hooks": [
+    {
+      "event": "task-completed",
+      "script": "${CLAUDE_PLUGIN_ROOT}/hooks/cleanup.sh",
+      "description": "Post-task cleanup: remove temp files, warn about unexpected root files, manage orphans"
+    }
+  ]
+}