docs: replace mermaid diagrams with PNG images for architecture and dispute lifecycle

Enhance documentation and address specification gaming in ChargebackOps

fix(eval): sequential per-checkpoint base load + product-grade docs

feat: Implement wait_for_updates action for handling delayed cases and evidence

feat: enhance completion parsing to handle truncated JSON and `<think>` blocks

feat: add per-family evaluation and plotting for training curves

feat: tighten EscalationROI, add ambiguous medium case, LLM note judge wrapper

feat: Add training curve evaluation and plotting utilities with unit tests

Add training notebook and benchmark runner for ChargebackOps

feat: Implement Issuer agent for multi-round dispute lifecycle

refactor: tighten rubric discrimination + LLM path + add running doc

refactor: update difficulty levels and enhance scoring rubrics in documentation and code

Add documentation for core modules, data assets, evaluation components, runners, and tests

Refactor evidence building and improve code readability in iso_adapter.py