build: Configure automatic versioning from git tags

- Use setuptools-scm for automatic version detection
- Version now automatically derived from git tags
- No need to manually update version in pyproject.toml
- Added _version.py to .gitignore

This enables automatic patch version bumping through git tags without
manually updating any configuration files.

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

Co-Authored-By: Claude <noreply@anthropic.com>

pyproject.toml

@@ -1,6 +1,10 @@
+[build-system]
+requires = ["setuptools>=61.0", "setuptools-scm>=8.0"]
+build-backend = "setuptools.build_meta"
+
 [project]
 name = "deltaglider"
-version = "0.1.0"
+dynamic = ["version"]
 description = "Store 4TB in 5GB: S3-compatible storage with 99.9% compression for versioned files"
 authors = [
     {name = "Beshu Tech", email = "info@beshu.tech"},
@@ -74,12 +78,6 @@ dev = [
 [project.scripts]
 deltaglider = "deltaglider.app.cli.main:main"
 
-[build-system]
-requires = ["hatchling"]
-build-backend = "hatchling.build"
-
-[tool.hatch.build.targets.wheel]
-packages = ["src/deltaglider"]
 
 [tool.hatch.build.targets.sdist]
 include = [
@@ -111,8 +109,15 @@ dev-dependencies = [
     "mypy>=1.13.0",
     "boto3-stubs[s3]>=1.35.0",
     "types-python-dateutil>=2.9.0",
+    "setuptools-scm>=8.0.0",
 ]
 
+[tool.setuptools_scm]
+# Automatically determine version from git tags
+write_to = "src/deltaglider/_version.py"
+version_scheme = "post-release"
+local_scheme = "no-local-version"
+
 [tool.ruff]
 target-version = "py311"
 line-length = 100