Initial commit: Invoice field extraction system using YOLO + OCR

Features:
- Auto-labeling pipeline: CSV values -> PDF search -> YOLO annotations
- Flexible date matching: year-month match, nearby date tolerance
- PDF text extraction with PyMuPDF
- OCR support for scanned documents (PaddleOCR)
- YOLO training and inference pipeline
- 7 field types: InvoiceNumber, InvoiceDate, InvoiceDueDate, OCR, Bankgiro, Plusgiro, Amount

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

configs/training.yaml

@@ -0,0 +1,59 @@
+# YOLO Training Configuration
+# Use with: yolo train data=dataset.yaml cfg=training.yaml
+
+# Model
+model: yolov8s.pt
+
+# Training hyperparameters
+epochs: 100
+patience: 20                  # Early stopping patience
+batch: 16
+imgsz: 1280
+
+# Optimizer
+optimizer: AdamW
+lr0: 0.001                    # Initial learning rate
+lrf: 0.01                     # Final learning rate factor
+momentum: 0.937
+weight_decay: 0.0005
+
+# Warmup
+warmup_epochs: 3
+warmup_momentum: 0.8
+warmup_bias_lr: 0.1
+
+# Loss weights
+box: 7.5                      # Box loss gain
+cls: 0.5                      # Class loss gain
+dfl: 1.5                      # DFL loss gain
+
+# Augmentation
+# Keep minimal for document images
+hsv_h: 0.0                    # No hue augmentation
+hsv_s: 0.1                    # Slight saturation
+hsv_v: 0.2                    # Brightness variation
+degrees: 5.0                  # Rotation ±5°
+translate: 0.05               # Translation
+scale: 0.2                    # Scale ±20%
+shear: 0.0                    # No shear
+perspective: 0.0              # No perspective
+flipud: 0.0                   # No vertical flip
+fliplr: 0.0                   # No horizontal flip
+mosaic: 0.0                   # Disable mosaic (not suitable for documents)
+mixup: 0.0                    # Disable mixup
+copy_paste: 0.0               # Disable copy-paste
+
+# Validation
+val: true
+save: true
+save_period: 10
+cache: true
+
+# Other
+device: 0                     # GPU device (0, 1, etc.) or 'cpu'
+workers: 8
+project: runs/train
+name: invoice_fields
+exist_ok: true
+pretrained: true
+verbose: true