build: switch from devenv to nix flakes with uv2nix

- Replace devenv setup with pure nix flakes using uv2nix, pyproject-nix,
  pyproject-build-systems, and git-hooks.nix (adapted from hokusai)
- Add forgejo CI pipeline with lint/check/test and build jobs
- Wrap cv binary with LD_LIBRARY_PATH for weasyprint native dependencies
- Move basedpyright to dev dependency group, add pytest and ruff
- Fix package imports to use hatch source remapping (src/ layout)
- Update .envrc to use flake, expand .gitignore

BREAKING CHANGE: devenv is no longer used, run direnv allow to reload

pyproject.toml

@@ -6,7 +6,6 @@ readme = "README.md"
 license = "MIT"
 requires-python = ">=3.13"
 dependencies = [
-    "basedpyright>=1.38.2",
     "jinja2>=3.1.6",
     "markdown>=3.7",
     "pydantic>=2.12.5",
@@ -15,6 +14,13 @@ dependencies = [
     "weasyprint>=68.1",
 ]
 
+[dependency-groups]
+dev = [
+    "basedpyright>=1.38.2",
+    "pytest>=9.0.2",
+    "ruff>=0.15.1",
+]
+
 [build-system]
 requires = ["hatchling"]
 build-backend = "hatchling.build"
@@ -22,5 +28,8 @@ build-backend = "hatchling.build"
 [tool.hatch.build.targets.wheel]
 packages = ["main.py", "src/cv_generator"]
 
+[tool.hatch.build.targets.wheel.sources]
+"src" = ""
+
 [project.scripts]
 cv = "main:app"