ci: add ruff linting and mypy type checking

Add ruff and mypy to dev dependencies with configuration in pyproject.toml.
Add a lint CI job that runs ruff check, ruff format --check, and mypy.
Auto-fix import sorting and formatting across the codebase. Exclude
alembic/versions from linting (auto-generated migrations). Ignore B008
(FastAPI Depends pattern) and RUF001 (unicode in user-facing strings).

21 ruff lint errors and 50 mypy errors remain for manual review.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

pyproject.toml

@@ -27,6 +27,8 @@ dependencies = [
 dev = [
   "pytest>=8.3,<9.0",
   "pytest-asyncio>=0.25,<0.26",
+  "ruff>=0.9",
+  "mypy>=1.14",
 ]
 
 [tool.pytest.ini_options]
@@ -41,6 +43,24 @@ markers = [
   "smoke: smoke tests for containerized runtime",
 ]
 
+[tool.ruff]
+target-version = "py312"
+line-length = 120
+extend-exclude = ["alembic/versions"]
+
+[tool.ruff.lint]
+select = ["E", "F", "W", "I", "UP", "B", "SIM", "RUF"]
+ignore = ["E501", "B008", "RUF001"]
+
+[tool.ruff.lint.isort]
+known-first-party = ["app"]
+
+[tool.mypy]
+python_version = "3.12"
+ignore_missing_imports = true
+check_untyped_defs = false
+warn_unused_ignores = true
+
 [tool.setuptools]
 include-package-data = true