feat: add system stats API for dashboard monitoring

- GET /tools/system/stats - Real-time host system statistics
- CPU usage, memory, all mounted disks, network I/O
- GPU/VRAM stats via nvidia-smi (if available)
- Uses psutil for cross-platform host metrics
- Auto-discovers and filters real filesystems

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

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

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "core-api"
-version = "1.6.1"
+version = "1.7.0"
 description = "Core Code API - Infrastructure management and tools API"
 readme = "README.md"
 requires-python = ">=3.12"