[GSoC] Build NER training dataset from annotated rules

[Kaushik-Kumar-CEG]

Tasks:

• Parse .RULE files and extract extract required phrase markers
• Propagate annotations (with CLI commands from Update rules with required phrases automatically #3924 ) to unannotated rules (with matching text) to expand the dataset
• Improve composite rules (AND/OR expressions where some aren't marked)
• Convert to BIOES labels
• Split into train/val/test by rule family
• Validate dataset quality

Timeline: Weeks 1-2 (current)

Deliverable: BIOES dataset ready for training (train/val/test splits)