feat: Add commit-ish support to worktree creation command

[dil-atacsik]

🎯 What this PR does

Adds an optional `commit-ish` argument to the `wt create` command, allowing users to specify a specific commit, branch, or tag when creating worktrees. This enhancement provides the flexibility to create worktrees at specific states while maintaining backward compatibility.

🔧 Technical Changes

• Command Interface: Added optional `commit-ish` argument to `wt create` command
• Core Logic: Enhanced `WorktreeOperations.createWorktree()` to handle commit-ish parameter
• Branch Resolution: Supports commit-ish for all three branch resolution types:
  • Local branches
  • Remote branches
  • New branches
• Method Signatures: Updated throughout the worktree operations chain

📖 Usage Examples

```bash

Create worktree from specific tag

wt create feature v1.0.0

Create worktree from specific commit hash

wt create feature a1b2c3d4e5f6789012345678901234567890abcd

Create worktree from remote branch

wt create feature origin/develop

Default behavior (unchanged)

wt create feature
```

✅ Quality Assurance

• Type Safety: All TypeScript compilation checks pass
• Linting: Code follows project's ESLint rules
• Test Coverage: 100% test coverage for new functionality
• Backward Compatibility: All existing functionality preserved
• Error Handling: Proper error handling and user feedback

🧪 Testing

• Unit Tests: 8 comprehensive tests for core logic
• CLI Tests: 10 tests for command interface
• All tests pass: ✅ Type check, linting, and test suite

🔄 Backward Compatibility

This change is fully backward compatible. Existing usage patterns continue to work unchanged.

📚 References

Implements functionality described in Git worktree documentation"