Fix tokenizer extra_special_tokens crash and stabilize transformers

feat: Add percentage progress to downloading status in UI and extension

feat: Add download status polling to UI and Firefox extension

feat: Add Global Saliency Calculation Mode

docs: update study intro text to reflect 3 conditions

feat: add gradient condition to user study and preference questionnaire

fix: ensure tokens without whitespace group correctly and update hardcoded html

fix: syntax error in static/index.html preventing user study from starting

feat: finalized FlowRead AI with hardcoded user study and polished UI

Hardcode study HTML to reduce API load

UI styling updates and README

Initial commit: text saliency pro with Gemma 2B