feat: Add totals from all filtered records to invoices, treasury, and trial balance

Previously, totals were computed client-side from only the current page data,
which gave incorrect results when paginating. Now the backend calculates totals
across ALL filtered records and returns them in the API response.

- Invoice: Add total_sold_all field for sum of all filtered invoice balances
- Treasury: Add sold_precedent_all, total_incasari_all, total_plati_all, sold_final_all
- Trial Balance: Add 6-column totals (debit/credit for each balance type)
- Frontend stores and views updated to use backend totals

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

reports-app/backend/app/models/invoice.py

@@ -64,6 +64,8 @@ class InvoiceListResponse(BaseModel):
     page_size: int
     has_more: bool
     accounting_period: Optional[dict] = Field(default=None, description="Perioada contabilă (an, luna)")
+    # Total sold din TOATE facturile filtrate (nu doar pagina curentă)
+    total_sold_all: Decimal = Field(default=Decimal('0.00'), description="Total sold din toate facturile filtrate")
 
 class InvoiceSummary(BaseModel):
     """Rezumat pentru facturi - pentru dashboard"""