(retriever) update graphic-elements stage

[edknv]

Description

This PR integrates the graphic-elements model with OCR for semantically-structured chart text extraction.

• New use_graphic_elements flag enables running the graphic-elements model on chart crops detected by page-elements, then combining those detections with OCR output via bounding box matching to produce text ordered by semantic role (title, axes, labels, legend) instead of plain reading-order concatenation.
• Supports both local and remote graphic-elements models; graphic_elements_invoke_url sends chart crops to a NIM endpoint; auto-enables use_graphic_elements when set.

Before (OCR only)

Chart 1
This chart shows some gadgets, and some very fictitious costs.
Gadgets and their cost
$160.00
$140.00
$120.00
$100.00
Dollars
$80.00
$60.00
$40.00
$20.00
$-
Powerdrill
Bluetooth speaker
Minifridge
Premium desk fan
Hammer
Cost

After (graphic-elements + OCR)

This chart shows some gadgets, and some very fictitious costs.   Minifridge - Premium desk fan - Hammer - Powerdrill - Bluetooth speaker Dollars Chart 1 $160.00 - $100.00 - $120.00 - $80.00 - $40.00 - $60.00 - $140.00 - $20.00 - $- Cost    Gadgets and their cost

Usage Examples

Inprocess (local models)

  python -m nemo_retriever.examples.inprocess_pipeline \
    /work/data/jp20 \
    --query-csv /work/data/jp20_query_gt.csv \
    --use-graphic-elements \
    --num-gpus 2

Inprocess (remote graphic-elements endpoint, local everything else)

  python -m nemo_retriever.examples.inprocess_pipeline \
    /work/data/jp20 \
    --graphic-elements-invoke-url http://localhost:8000/v1/infer \
    --num-gpus 2

Batch (all local)

  python -m nemo_retriever.examples.batch_pipeline \
    /work/data/jp20 \
    --use-graphic-elements \
    --gpu-page-elements 0.5 \
    --gpu-ocr 1.0 \
    --gpu-embed 0.5 \
    --ocr-workers 3 \
    --page-elements-workers 3

Batch (remote graphic-elements endpoint, local page-elements + OCR)

  python -m nemo_retriever.examples.batch_pipeline \
    /work/data/jp20 \
    --graphic-elements-invoke-url http://localhost:8000/v1/infer \
    --gpu-page-elements 0.5 \
    --gpu-ocr 1.0 \
    --gpu-embed 0.5

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.
• If adjusting docker-compose.yaml environment variables have you ensured those are mimicked in the Helm values.yaml file.