fix: correct CLI entry point and use 'type' field instead of 'command'

Fixed two critical issues from step 1:

1. CLI Entry Point:
   - Correct command: 'deepks' (not 'python main.py')
   - Entry point: main.py in project root
   - setup.py points to main:main
   - Installed via: pip install -e .

2. Configuration Field:
   - Use 'type' field (not 'command')
   - Valid types: train, test, scf, stats, iterate
   - Updated all code and tests to use 'type'

Changes:
- main.py: Unified entry point in project root
- setup.py: Updated entry_points to use main:main
- deepks/cli/main.py: Changed 'command' to 'type'
- deepks/io/input/dispatcher.py: Use 'type' field
- deepks/io/input/defaults.py: Updated function parameter
- tests/unit/test_unified_cli.py: Updated all tests
- .gitignore: Added .claude/ to ignore list
- Removed .claude/ and docs/skills/ from repository

Usage:
  deepks                 # Uses input.yaml (default)
  deepks my_config.yaml  # Uses specified config
  deepks --help          # Show help

Config file format:
  type: scf              # Required field
  scf_soft: pyscf        # Optional
  systems: [...]

Tests:
- All 101 tests passing
- 5 tests skipped (expected)

This aligns with docs/input-parameter.md specification.

Author: ErjieWu

.claude/skills/deepks-refactoring-plan.md

@@ -5,6 +5,7 @@ model.ckpt.*
 .vscode
 .ipynb_*
 *.swp
+.claude/
 
 # Byte-compiled / optimized / DLL files
 __pycache__/