feat: Enhance invoice management with PDF optimization and date fixes

Optimize PDF export layout with compact columns and more space for partner names.
Add accounting period display to invoices matching Trial Balance format. Fix date
filtering to use local timezone instead of UTC. Update invoice ordering to
chronological sequence (DATAACT, NRACT, NUME).

**Backend changes:**
- Add accounting period query from calendar table
- Add currency (valuta) and cont filter support
- Change invoice ordering to chronological (DATAACT ASC, NRACT ASC, NUME)
- Add accounting_period field to InvoiceListResponse model

**Frontend changes:**
- Optimize PDF column widths (37% for partner names, compact numeric columns)
- Add custom column width support in exportUtils
- Fix date conversion from UTC to local timezone (prevents day shift)
- Add accounting period display in PDF exports
- Enhance E2E test coverage

**Cleanup:**
- Remove obsolete Trial Balance feature documentation

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

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

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

@@ -15,6 +15,8 @@ class InvoiceBase(BaseModel):
     contract: Optional[str] = Field(description="Numărul contractului")
     cod_fiscal: Optional[str] = Field(description="Codul fiscal")
     reg_comert: Optional[str] = Field(description="Registrul comerțului")
+    cont: Optional[str] = Field(description="Contul contabil")
+    valuta: str = Field(default="RON", description="Valuta (RON, EUR, USD, etc.)")
 
 class Invoice(InvoiceBase):
     """Model complet pentru factură cu calcule financiare"""
@@ -45,11 +47,12 @@ class InvoiceFilter(BaseModel):
     date_from: Optional[date] = Field(description="Data de început")
     date_to: Optional[date] = Field(description="Data de sfârșit")
     partner_name: Optional[str] = Field(description="Filtru după nume")
+    cont: Optional[str] = Field(description="Filtru după cont contabil")
     only_unpaid: bool = Field(default=True, description="Doar neachitate")
     min_amount: Optional[Decimal] = Field(description="Suma minimă")
     max_amount: Optional[Decimal] = Field(description="Suma maximă")
     page: int = Field(default=1, ge=1, description="Pagina")
-    page_size: int = Field(default=50, ge=1, le=1000, description="Mărimea paginii")
+    page_size: int = Field(default=50, ge=1, le=10000000, description="Mărimea paginii")
 
 class InvoiceListResponse(BaseModel):
     """Răspuns pentru lista de facturi"""
@@ -60,6 +63,7 @@ class InvoiceListResponse(BaseModel):
     page: int
     page_size: int
     has_more: bool
+    accounting_period: Optional[dict] = Field(default=None, description="Perioada contabilă (an, luna)")
 
 class InvoiceSummary(BaseModel):
     """Rezumat pentru facturi - pentru dashboard"""