feat: Improve OCR adaptive pipeline with early exit and better pattern matching

- Add adaptive 3-step OCR pipeline with early exit when all 5 fields found
- Add pattern for "C. I. F." with spaces (OCR artifact from PaddleOCR)
- Add pattern for YYYY. MM. DD date format with spaces (OMV/Petrom receipts)
- Add pattern for "OTAL TAXE" with T cut off and reversed amount position
- Make TVA rate pattern more flexible (code letter optional, handle "-21%")
- Replace logger.info with print(flush=True) for better debugging visibility
- Improve OCRPreview.vue to show extraction progress and raw OCR text

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

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

data-entry-app/backend/app/schemas/ocr.py

@@ -37,6 +37,8 @@ class ExtractionData(BaseModel):
     confidence_vendor: float = Field(default=0.0, ge=0, le=1, description="Vendor extraction confidence")
     overall_confidence: float = Field(default=0.0, ge=0, le=1, description="Overall confidence score")
     raw_text: str = Field(default="", description="Raw OCR text")
+    ocr_engine: str = Field(default="", description="OCR engine used: paddleocr or tesseract")
+    processing_time_ms: int = Field(default=0, ge=0, description="Processing time in milliseconds")
 
     class Config:
         """Pydantic config."""