feat: add VS Code installation following spilled coffee principle

## Problem Statement
Need VS Code installed for read-only code browsing purposes, aligning with the spilled coffee principle. While the current workflow emphasizes tmux + git worktrees + Claude Code for OSE principle adherence, VS Code serves a specific use case for visual code exploration.

## Requirements
- Command `code .` should open VS Code in the current directory
- Installation must be automated and reproducible (spilled coffee principle)
- Script should detect and handle existing installations gracefully
- Must work across Linux and macOS environments
- Should integrate with existing dotfiles installation patterns

## Proposed Implementation

### Minimal Approach
1. Create `utils/install-vscode.sh` following the pattern of existing installers (e.g., `install-neovim.sh`)
2. Add VS Code installation to appropriate setup flow
3. Ensure proper PATH configuration for the `code` command

### Installation Script Structure
```bash
#!/bin/bash
# VS Code Installation Utility
# Automated installation following the spilled coffee principle

# Source common logging functions
source "${SCRIPT_DIR}/logging.sh"

install_vscode() {
# Check if already installed
# Platform-specific installation:
# - macOS: brew install --cask visual-studio-code
# - Linux: snap/apt/official Microsoft repo
# Verify installation
# Set up PATH if needed
}
```

## Definition of Done
- [ ] `utils/install-vscode.sh` script created
- [ ] Script handles multiple platforms (Linux/macOS)
- [ ] Script detects existing installations
- [ ] `code .` command works after installation
- [ ] Script follows existing logging patterns
- [ ] Script is idempotent (can run multiple times safely)
- [ ] Documentation updated if needed

## Notes
- This aligns with OSE principle by providing a read-only view tool
- Not replacing the primary tmux + Claude Code workflow
- Follows spilled coffee principle for reproducible setup

Start by reading utils/install-neovim.sh and the shared logging.sh pattern, then trace the existing setup flow where installers are invoked. Implement the requested VS Code installer across Linux and macOS, including safe reruns and code command verification, and confirm that the documented definition of done is met.

Written by the indexing model from the issue text.