Track water and sleep with JSON file storage
- Renamed skill from "health-tracker" to "healthcheck" - Simplified and rewrote documentation for conciseness and clarity - Shortened all Node.js one-liners for recording and managing water and sleep data - Updated data format: renamed fields (e.g., "timestamp" → "time"), edited usage examples - Removed metadata and some advanced examples (e.g., reminders, detailed stats) - Focused on essential file operations: add, update, delete, and stats for water/sleep records