feat: Add multiple TVA entries support for Romanian receipts

- Add TvaEntry schema supporting multiple TVA rates (A, B, C, D codes)
- Update OCR extractor to extract multiple TVA entries from receipts
- Support both old (19%, 9%, 5%) and new Romanian rates (21%, 11% from Aug 2025)
- Add tva_breakdown, tva_total, items_count, vendor_address to Receipt model
- Update OCRPreview.vue to display TVA entries with rate badges
- Add "Detalii Suplimentare" section in ReceiptCreateView with editable TVA table
- Add TVA breakdown display in ReceiptDetailView
- Create database migration for new TVA columns

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

data-entry-app/backend/migrations/versions/20251212_140422_add_tva_breakdown_to_receipt.py

@@ -0,0 +1,37 @@
+"""add_tva_breakdown_to_receipt
+
+Revision ID: 1cfb423c6953
+Revises: 001_initial
+Create Date: 2025-12-12 14:04:22.464289+00:00
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+import sqlmodel
+
+
+# revision identifiers, used by Alembic.
+revision: str = '1cfb423c6953'
+down_revision: Union[str, None] = '001_initial'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    # Add TVA-related columns to receipts table
+    with op.batch_alter_table('receipts', schema=None) as batch_op:
+        batch_op.add_column(sa.Column('tva_breakdown', sqlmodel.sql.sqltypes.AutoString(length=1000), nullable=True))
+        batch_op.add_column(sa.Column('tva_total', sa.Numeric(precision=15, scale=2), nullable=True))
+        batch_op.add_column(sa.Column('items_count', sa.Integer(), nullable=True))
+        batch_op.add_column(sa.Column('vendor_address', sqlmodel.sql.sqltypes.AutoString(length=500), nullable=True))
+
+
+def downgrade() -> None:
+    # Remove TVA-related columns from receipts table
+    with op.batch_alter_table('receipts', schema=None) as batch_op:
+        batch_op.drop_column('vendor_address')
+        batch_op.drop_column('items_count')
+        batch_op.drop_column('tva_total')
+        batch_op.drop_column('tva_breakdown')