feat: upgrade PaddlePaddle and PaddleOCR to 3.x

- Update paddlepaddle from >=2.5.0 to >=3.0.0,<3.3.0
- Update paddleocr from >=2.7.0 to >=3.0.0
- Update paddlepaddle-gpu from >=2.5.0 to >=3.0.0,<3.3.0

Note: PaddlePaddle 3.3.0 has an OneDNN bug that breaks CPU inference
(ConvertPirAttribute2RuntimeAttribute not implemented). Using <3.3.0
until the bug is fixed upstream.

This upgrade enables PP-StructureV3 for table extraction and uses
PP-OCRv5 for improved text recognition accuracy. The existing codebase
is already compatible with the 3.x API (predict() method and new
response format).

Verified:
- PaddleOCR import works
- PPStructureV3 is available
- OCREngine initializes correctly
- Inference API returns correct field extractions
- 2117 unit tests pass

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

requirements.txt

@@ -4,8 +4,8 @@
 PyMuPDF>=1.23.0              # PDF rendering and text extraction
 
 # OCR
-paddlepaddle>=2.5.0          # PaddlePaddle framework
-paddleocr>=2.7.0             # PaddleOCR
+paddlepaddle>=3.0.0,<3.3.0   # PaddlePaddle framework (3.3.0 has OneDNN bug)
+paddleocr>=3.0.0             # PaddleOCR (PP-OCRv5)
 
 # YOLO
 ultralytics>=8.1.0           # YOLOv8/v11