Fix flake8 and mypy linting errors

- Update .flake8 and pre-commit config to properly use flake8 config
- Add B008 to ignored errors (FastAPI Depends pattern)
- Add E402 to ignored errors (intentional module-level imports)
- Remove unused imports from test files and source files
- Fix f-strings without placeholders
- Add type annotations to inner async functions
- Fix SQLAlchemy execute() to use text() wrapper
- Add type: ignore comments for alembic.command imports
- Exclude alembic/ directory from mypy in pre-commit
- Update mypy overrides for test files to not require type annotations
- Fix type annotations for params dicts in web routes
- Fix generator return type in test fixtures

.pre-commit-config.yaml

@@ -21,6 +21,7 @@ repos:
     rev: 7.0.0
     hooks:
       - id: flake8
+        args: ["--config=.flake8"]
         additional_dependencies:
           - flake8-bugbear
           - flake8-comprehensions
@@ -29,6 +30,7 @@ repos:
     rev: v1.9.0
     hooks:
       - id: mypy
+        exclude: ^alembic/
         additional_dependencies:
           - pydantic>=2.0.0
           - pydantic-settings>=2.0.0