chore: optimize package contents for distribution (#9)

Configure hatchling to exclude unnecessary files from the source
distribution (sdist). This reduces package size and ensures only
essential files are distributed to users.

Excluded from sdist:
- .github/ - CI/CD workflows and GitHub-specific configs
- tests/ - Test suite (not needed by end users)
- CHANGELOG.md - Auto-generated, tracked in GitHub releases
- AGENTS.md, CLAUDE.md - Developer documentation
- release-please-config.json - Release automation config
- .release-please-manifest.json - Release version tracking
- renovate.json - Dependency update automation
- uv.lock - Development lock file

The wheel (binary) distribution already only includes the necessary
Python code and is unchanged.

Before:
- sdist included ~15 files (tests, .github, configs, etc.)

After:
- sdist includes only 7 essential files (src/, LICENSE, README, pyproject.toml)
- wheel unchanged (still optimal with just Python code)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: mldangelo

pyproject.toml

@@ -45,6 +45,23 @@ Repository = "https://github.com/promptfoo/promptfoo-python"
 Homepage = "https://www.promptfoo.dev"
 Documentation = "https://www.promptfoo.dev/docs"
 
+[tool.hatch.build.targets.sdist]
+exclude = [
+    "/.github",
+    "/.gitignore",
+    "/.release-please-manifest.json",
+    "/release-please-config.json",
+    "/renovate.json",
+    "/uv.lock",
+    "/tests",
+    "/CHANGELOG.md",
+    "/AGENTS.md",
+    "/CLAUDE.md",
+]
+
+[tool.hatch.build.targets.wheel]
+packages = ["src/promptfoo"]
+
 [tool.ruff]
 line-length = 120
 target-version = "py39"