feat: add unified linting scripts and git hooks for code quality enforcement

- Introduced `lint` and `lint-fix` applications in `flake.nix` for unified linting of backend (Python) and frontend (TypeScript/Svelte) code.
- Added `scripts/lint.sh` for manual linting execution.
- Created `scripts/install-hooks.sh` to set up git hooks for automatic linting before commits and optional tests before pushes.
- Updated `README.md` with instructions for using the new linting features and git hooks.

backend/pyproject.toml

@@ -33,10 +33,6 @@ requires = ["setuptools>=61.0"]
 build-backend = "setuptools.build_meta"
 
 [tool.ruff]
-# Enable pycodestyle (`E`), Pyflakes (`F`), isort (`I`)
-select = ["E", "F", "I", "W", "N", "UP", "B", "C4", "SIM"]
-ignore = []
-
 # Exclude common paths
 exclude = [
     ".git",
@@ -46,16 +42,24 @@ exclude = [
     "alembic/versions",
 ]
 
-# Same as Black.
-line-length = 100
-
-# Allow unused variables when underscore-prefixed.
-dummy-variable-rgx = "^(_+|(_+[a-zA-Z0-9_]*[a-zA-Z0-9]+?))$"
+# Line length (slightly longer for SQLAlchemy models)
+line-length = 120
 
 # Target Python 3.12
 target-version = "py312"
 
-[tool.ruff.per-file-ignores]
+[tool.ruff.lint]
+# Enable pycodestyle (`E`), Pyflakes (`F`), isort (`I`)
+select = ["E", "F", "I", "W", "N", "UP", "B", "C4", "SIM"]
+ignore = [
+    "B008",  # Allow Depends() in FastAPI function defaults
+    "N818",  # Allow WebRefException without Error suffix
+]
+
+# Allow unused variables when underscore-prefixed.
+dummy-variable-rgx = "^(_+|(_+[a-zA-Z0-9_]*[a-zA-Z0-9]+?))$"
+
+[tool.ruff.lint.per-file-ignores]
 "__init__.py" = ["F401"]  # Allow unused imports in __init__.py
 "tests/*" = ["S101"]  # Allow assert in tests