feat: add version management with setuptools-scm

- Configure hatch-vcs for automatic version generation from git tags
- Update pyproject.toml to use dynamic versioning
- Add src/_version.py for runtime version access
- Update src/__init__.py to import version from _version
- Add __APP_VERSION__ to frontend vite config
- Add version script to frontend package.json
- Update CI workflows to trigger on version tags instead of branches

pyproject.toml

@@ -1,10 +1,10 @@
 [build-system]
-requires = ["hatchling"]
+requires = ["hatchling", "hatch-vcs"]
 build-backend = "hatchling.build"
 
 [project]
 name = "aether"
-version = "1.0.0"
+dynamic = ["version"]
 description = "Proxy server enabling Claude Code to work with OpenAI-compatible API providers"
 readme = "README.md"
 authors = [
@@ -76,6 +76,7 @@ dev-dependencies = [
     "isort>=5.12.0",
     "mypy>=1.0.0",
     "pyinstaller>=6.15.0",
+    "hatch-vcs>=0.5.0",
 ]
 
 [tool.black]
@@ -89,6 +90,12 @@ line_length = 100
 [tool.hatch.build.targets.wheel]
 packages = ["src"]
 
+[tool.hatch.version]
+source = "vcs"
+
+[tool.hatch.build.hooks.vcs]
+version-file = "src/_version.py"
+
 [tool.mypy]
 python_version = "3.9"
 warn_return_any = true