Add Windows support and cross-platform hook system

[nhorton]

Summary

This PR adds full Windows support to DeepWork and refactors the hook system to be cross-platform. The main changes include:

1. Windows Installation & Distribution: Added PowerShell-based installer scripts and PyInstaller configuration to build standalone Windows executables that can be distributed without Python.

2. Cross-Platform Hook System: Migrated from shell script-based hooks to Python module-based hooks that work on Windows, macOS, and Linux without requiring bash.

3. Documentation: Added comprehensive Windows installation guide and updated README with Windows support information.

Key Changes

Windows Support

• scripts/build-windows.ps1: PowerShell script to build standalone Windows executable using PyInstaller
• scripts/install-windows.ps1: PowerShell installer that downloads/installs DeepWork and adds it to user PATH
• scripts/install-windows.bat: Batch wrapper for PowerShell installer
• .github/workflows/build-windows.yml: GitHub Actions workflow to automatically build and release Windows executables
• scripts/deepwork.spec: PyInstaller spec file for building the Windows executable
• doc/installation/windows.md: Comprehensive Windows installation guide with troubleshooting

Cross-Platform Hook System

• src/deepwork/hooks/user_prompt_submit.py: New Python module hook (replaces shell script) that captures work tree state at prompt submission
• src/deepwork/hooks/capture_prompt.py: Cross-platform work tree capture utility (replaces capture_prompt_work_tree.sh)
• src/deepwork/hooks/hook_entry.py: Entry point for invoking hooks via deepwork hook <name> command
• Updated hook configuration: Changed from shell script paths to deepwork hook <name> commands in settings files

Code Updates

• src/deepwork/core/hooks_syncer.py: Updated to generate cross-platform commands and use forward slashes in paths (works in bash on all platforms)
• src/deepwork/core/adapters.py: Removed Windows-specific bash permission requirement for job scripts (no longer needed with Python hooks)
• .claude/settings.json: Updated hook configuration to use deepwork hook commands
• .deepwork/jobs/deepwork_rules/hooks/global_hooks.yml: Migrated to Python module-based hooks
• src/deepwork/hooks/__init__.py: Updated documentation to reflect cross-platform approach

Tests

• tests/unit/test_cross_platform_hooks.py: New test suite for cross-platform hook implementations
• tests/unit/test_adapters.py: Updated permission count assertions (removed job script bash permission)

Documentation

• README.md: Added Windows platform support note and Windows installation section
• .gitignore: Added exception to keep scripts/deepwork.spec in version control

Implementation Details

Why Python Modules for Hooks?

• Cross-platform compatibility: Works on Windows, macOS, and Linux without bash dependencies
• Consistent behavior: Same code path regardless of platform or installation method
• Better integration: Hooks can directly import DeepWork modules instead of shelling out

Path Handling

• Hook commands use forward slashes (e.g., .deepwork/jobs/test/hooks/script.sh) which work in bash on all platforms including Windows (via Git Bash/WSL)
• The deepwork hook <name> command works everywhere regardless of how DeepWork was installed (pip, pipx, Windows EXE, etc.)

Windows Executable Distribution

• PyInstaller bundles Python and all dependencies into a single .exe file
• GitHub Actions automatically builds and releases Windows executables on each release
• Users can download pre-built executables or build from source