feat: add deposit edit and delete for pending deposits

Add PUT /api/v1/dca/deposits/{id} endpoint to update amount, currency,
and notes on pending deposits. Add DELETE endpoint to remove deposits
not yet inserted into the machine. Both endpoints reject confirmed
deposits. Frontend now shows edit/delete buttons only for pending rows.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

models.py

@@ -60,6 +60,18 @@ class DcaDeposit(BaseModel):
     confirmed_at: Optional[datetime]
 
 
+class UpdateDepositData(BaseModel):
+    amount: Optional[float] = None
+    currency: Optional[str] = None
+    notes: Optional[str] = None
+
+    @validator('amount')
+    def round_amount_to_cents(cls, v):
+        if v is not None:
+            return round(float(v), 2)
+        return v
+
+
 class UpdateDepositStatusData(BaseModel):
     status: str
     notes: Optional[str] = None