feat: Add currency and unit support across models, routes, and templates; enhance UI for consumption, costs, and production

models/capex.py

@@ -10,8 +10,12 @@ class Capex(Base):
     scenario_id = Column(Integer, ForeignKey("scenario.id"), nullable=False)
     amount = Column(Float, nullable=False)
     description = Column(String, nullable=True)
+    currency_code = Column(String(3), nullable=False, default="USD")
 
     scenario = relationship("Scenario", back_populates="capex_items")
 
     def __repr__(self):
-        return f"<Capex id={self.id} scenario_id={self.scenario_id} amount={self.amount}>"
+        return (
+            f"<Capex id={self.id} scenario_id={self.scenario_id} "
+            f"amount={self.amount} currency={self.currency_code}>"
+        )