feat: add qa_build mode, tests, and region mode support

Router Configuration:
- Add mode='qa_build' routing rule in router-config.yml
- Priority 8, uses local_qwen3_8b for Q&A generation

2-Stage Q&A Pipeline Tests:
- Create test_qa_pipeline.py with comprehensive tests
- Test prompt building, JSON parsing, router integration
- Mock DAGI Router responses for testing

Region Mode (Grounding OCR):
- Add region_bbox and region_page parameters to ParseRequest
- Support region mode in local_runtime with bbox in prompt
- Update endpoints to accept region parameters (x, y, width, height, page)
- Validate region parameters and filter pages for region mode
- Pass region_bbox through inference pipeline

Updates:
- Update local_runtime to support region_bbox in prompts
- Update inference.py to pass region_bbox to local_runtime
- Update endpoints.py to handle region mode parameters

services/parser-service/app/schemas.py

@@ -120,6 +120,9 @@ class ParseRequest(BaseModel):
     )
     dao_id: Optional[str] = Field(None, description="DAO ID")
     doc_id: Optional[str] = Field(None, description="Document ID")
+    # Region mode parameters (for grounding OCR)
+    region_bbox: Optional[BBox] = Field(None, description="Bounding box for region mode (x, y, width, height)")
+    region_page: Optional[int] = Field(None, description="Page number for region mode")
 
 
 class ParseResponse(BaseModel):