Add comprehensive security and contribution documentation

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

pyproject.toml

@@ -0,0 +1,72 @@
+[tool.black]
+line-length = 100
+target-version = ['py310']
+include = '\.pyi?$'
+extend-exclude = '''
+/(
+  # directories
+  \.eggs
+  | \.git
+  | \.hg
+  | \.mypy_cache
+  | \.tox
+  | \.venv
+  | venv
+  | _build
+  | buck-out
+  | build
+  | dist
+)/
+'''
+
+[tool.isort]
+profile = "black"
+line_length = 100
+multi_line_output = 3
+include_trailing_comma = true
+force_grid_wrap = 0
+use_parentheses = true
+ensure_newline_before_comments = true
+
+[tool.pytest.ini_options]
+testpaths = ["backend/app/tests"]
+python_files = ["test_*.py"]
+python_classes = ["Test*"]
+python_functions = ["test_*"]
+addopts = [
+    "--verbose",
+    "--strict-markers",
+    "--tb=short",
+]
+markers = [
+    "slow: marks tests as slow",
+    "integration: marks tests as integration tests",
+    "security: marks tests as security-related",
+]
+
+[tool.coverage.run]
+source = ["backend/app"]
+omit = [
+    "*/tests/*",
+    "*/venv/*",
+    "*/__pycache__/*",
+    "*/migrations/*",
+]
+
+[tool.coverage.report]
+precision = 2
+show_missing = true
+skip_covered = false
+
+[tool.mypy]
+python_version = "3.10"
+warn_return_any = true
+warn_unused_configs = true
+disallow_untyped_defs = false
+check_untyped_defs = true
+ignore_missing_imports = true
+no_implicit_optional = true
+warn_redundant_casts = true
+warn_unused_ignores = true
+warn_no_return = true
+strict_optional = true