Add version command with comprehensive unit tests and build integration

- Implement llama version command with table and JSON output formats
- Add build-time git information capture via scripts/generate_build_info.py
- Include comprehensive unit test suite (test_version.py, test_version_simple.py, test_version_integration.py)
- Add build system integration with custom setup.py command
- Update .gitignore to exclude generated build info file

Features:
- Display Llama Stack and client versions
- Show Python version and build information (git commit, date, branch, tag)
- Optional component/provider listing organized by API
- Support for both table and JSON output formats
- Build-time capture of git metadata for version tracking

Testing:
- 8 unit tests covering all functionality
- Integration tests for CLI execution
- Simple dependency-free validation tests
- Documentation for test suite and build process

Signed-off-by: Akram Ben Aissi <akram.benaissi@gmail.com>

scripts/README.md

@@ -0,0 +1,47 @@
+# Build Scripts
+
+This directory contains scripts used during the build process.
+
+## generate_build_info.py
+
+This script generates `llama_stack/cli/build_info.py` with hardcoded git information at build time. This ensures that version information is captured at build time rather than being read dynamically at runtime.
+
+### Usage
+
+The script is automatically run during the build process via the custom `BuildWithBuildInfo` class in `setup.py`. You can also run it manually:
+
+```bash
+python scripts/generate_build_info.py
+```
+
+### Generated Information
+
+The script captures the following information:
+- Git commit hash (short form)
+- Git commit date
+- Git branch name
+- Git tag (latest)
+- Build timestamp
+
+### CI/CD Integration
+
+The script handles common CI/CD scenarios:
+- Detached HEAD state (common in CI environments)
+- Missing git information (fallback to environment variables)
+- Git not available (fallback to "unknown" values)
+
+### Environment Variables
+
+When running in CI/CD environments where the branch name might not be available via git (detached HEAD), the script checks these environment variables:
+- `GITHUB_REF_NAME` (GitHub Actions)
+- `CI_COMMIT_REF_NAME` (GitLab CI)
+- `BUILDKITE_BRANCH` (Buildkite)
+- `TRAVIS_BRANCH` (Travis CI)
+
+### Build Integration
+
+The build info generation is integrated into the build process via:
+1. `setup.py` - Custom build command that runs the script before building
+2. `pyproject.toml` - Standard Python package configuration
+
+This ensures that every build includes up-to-date git information without requiring runtime git access.