feat: add 'Search' option to selection popup so users can search highlighted text directly in the database

feat(ai): update AI Chat color scheme to modern Zen Teal & Emerald palette

fix: merge adjacent <B> headings with <I> footnote refs, fix marker normalization exclusion list

feat: normalize reference extraction and popup UI

feat: enhance footnote extraction and display at bottom of page

feat: implement Reference Lookup API and ReferencePopup integration

feat: migrate jina v5, refine AI popup, add reference popup UI

fix: copy confirmation icon not showing — race condition with selection-clear

ui: copy confirmation now shows green circle-checkmark ✅

fix: SelectionPopup positioning + AI citation hallucination