Add dashboard endpoint

backend/app/schemas/dashboard.py

@@ -0,0 +1,25 @@
+from decimal import Decimal
+from typing import Optional
+from pydantic import BaseModel
+
+from app.schemas.transaction import Transaction
+from app.util.encoders import decimal_encoder
+
+class DashboardStats(BaseModel):
+    transaction_count: int
+    transaction_count_previous: int
+    transaction_energy_total: Decimal
+    transaction_energy_total_previous: Decimal
+    transaction_cost_total: Decimal
+    transaction_cost_total_previous: Decimal
+
+    class Config:
+        json_encoders = {Decimal: decimal_encoder}
+
+class DashboardResponse(BaseModel):
+    stats: DashboardStats
+    current_transaction: Optional[Transaction] = None
+    recent_transactions: list[Transaction]
+
+    class Config:
+        json_encoders = {Decimal: decimal_encoder}