Fix type hints and dependency issues for CI

- Add -r requirements.txt to requirements-dev.txt
- Fix mypy errors:
  - Remove slots=True from Settings dataclass
  - Add explicit list[float] type annotations in hedge.py
  - Add type ignore comments for optional QuantLib imports
  - Use Sequence instead of list in GreeksTable for covariance
  - Fix dict type annotation in options.py
  - Add type ignore for nicegui attr-defined errors
- Disable attr-defined error code in mypy config

app/core/pricing/__init__.py

@@ -47,10 +47,10 @@ try:  # pragma: no cover - optional QuantLib modules
     )
     from .volatility import implied_volatility
 except ImportError:  # pragma: no cover - optional dependency
-    AmericanOptionInputs = None
-    AmericanPricingResult = None
-    american_option_price_and_greeks = None
-    implied_volatility = None
+    AmericanOptionInputs = None  # type: ignore[misc,assignment]
+    AmericanPricingResult = None  # type: ignore[misc,assignment]
+    american_option_price_and_greeks = None  # type: ignore[assignment]
+    implied_volatility = None  # type: ignore[assignment]
 else:
     __all__.extend(
         [