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

models/consumption.py

@@ -10,8 +10,13 @@ class Consumption(Base):
     scenario_id = Column(Integer, ForeignKey("scenario.id"), nullable=False)
     amount = Column(Float, nullable=False)
     description = Column(String, nullable=True)
+    unit_name = Column(String(64), nullable=True)
+    unit_symbol = Column(String(16), nullable=True)
 
     scenario = relationship("Scenario", back_populates="consumption_items")
 
     def __repr__(self):
-        return f"<Consumption id={self.id} scenario_id={self.scenario_id} amount={self.amount}>"
+        return (
+            f"<Consumption id={self.id} scenario_id={self.scenario_id} "
+            f"amount={self.amount} unit={self.unit_symbol or self.unit_name}>"
+        )