Add pre-commit framework

- Install pre-commit
- Configure .pre-commit-config.yaml with:
  - ruff (lint + format) for Python
  - bandit for Python security
  - eslint for TypeScript
  - prettier for TypeScript
  - shared constants validation
- Add Makefile targets: pre-commit, lint

.pre-commit-config.yaml

@@ -0,0 +1,41 @@
+repos:
+  - repo: https://github.com/astral-sh/ruff-pre-commit
+    rev: v0.14.0
+    hooks:
+      - id: ruff
+        args: [--fix]
+        files: ^backend/
+      - id: ruff-format
+        files: ^backend/
+
+  - repo: https://github.com/PyCQA/bandit
+    rev: 1.8.0
+    hooks:
+      - id: bandit
+        args: [-c, backend/pyproject.toml, -r]
+        files: ^backend/
+        exclude: ^backend/(tests|\.venv)/
+
+  - repo: local
+    hooks:
+      - id: eslint
+        name: ESLint
+        entry: npm run lint --prefix frontend
+        language: system
+        files: ^frontend/.*\.(ts|tsx)$
+        pass_filenames: false
+
+      - id: prettier
+        name: Prettier
+        entry: npm run format:check --prefix frontend
+        language: system
+        files: ^frontend/
+        pass_filenames: false
+
+      - id: check-constants
+        name: Check shared constants
+        entry: bash -c 'cd backend && uv run python validate_constants.py'
+        language: system
+        files: shared/constants\.json$
+        pass_filenames: false
+

Makefile

@@ -1,4 +1,4 @@
-.PHONY: install-backend install-frontend install setup-hooks backend frontend db db-stop db-ready db-seed dev test test-backend test-frontend test-e2e typecheck generate-types generate-types-standalone check-types-fresh check-constants lint-backend format-backend fix-backend security-backend lint-frontend fix-frontend format-frontend
+.PHONY: install-backend install-frontend install setup-hooks backend frontend db db-stop db-ready db-seed dev test test-backend test-frontend test-e2e typecheck generate-types generate-types-standalone check-types-fresh check-constants lint-backend format-backend fix-backend security-backend lint-frontend fix-frontend format-frontend pre-commit lint
 
 -include .env
 export
@@ -114,3 +114,9 @@ fix-frontend:
 
 format-frontend:
 	cd frontend && npm run format
+
+pre-commit:
+	cd backend && uv run pre-commit run --all-files
+
+lint: lint-backend lint-frontend security-backend
+	@echo "All linting passed!"

backend/pyproject.toml

@@ -23,6 +23,7 @@ dev = [
     "ruff>=0.14.10",
     "pytest-cov>=7.0.0",
     "bandit>=1.9.2",
+    "pre-commit>=4.5.1",
 ]
 
 [tool.mypy]