Initial commit: Vault Dashboard for options hedging

- FastAPI + NiceGUI web application
- QuantLib-based Black-Scholes pricing with Greeks
- Protective put, laddered, and LEAPS strategies
- Real-time WebSocket updates
- TradingView-style charts via Lightweight-Charts
- Docker containerization
- GitLab CI/CD pipeline for VPS deployment
- VPN-only access configuration

app/strategies/base.py

@@ -0,0 +1,40 @@
+from __future__ import annotations
+
+from abc import ABC, abstractmethod
+from dataclasses import dataclass
+
+from app.models.portfolio import LombardPortfolio
+
+
+@dataclass(frozen=True)
+class StrategyConfig:
+    """Common research inputs used by all strategy implementations."""
+
+    portfolio: LombardPortfolio
+    spot_price: float
+    volatility: float
+    risk_free_rate: float
+
+
+class BaseStrategy(ABC):
+    """Abstract strategy interface for paper-based hedge analysis."""
+
+    def __init__(self, config: StrategyConfig) -> None:
+        self.config = config
+
+    @property
+    @abstractmethod
+    def name(self) -> str:  # pragma: no cover - interface only
+        raise NotImplementedError
+
+    @abstractmethod
+    def calculate_cost(self) -> dict:
+        raise NotImplementedError
+
+    @abstractmethod
+    def calculate_protection(self) -> dict:
+        raise NotImplementedError
+
+    @abstractmethod
+    def get_scenarios(self) -> list[dict]:
+        raise NotImplementedError