refactor: organize project layout and Reader responsibilities

fix: restore Reader cache reuse and opening recovery

fix: repair Reader media playback and toolbar compatibility

perf: warm reader shell and reuse cached startup resources

perf: recover PDF demand pages and cache native search text

chore: upgrade search and Reader dependencies

perf: reuse heading geometry and share bounded PDF demand ranges

feat: consume versioned v3 PDF preview and text layers

fix: prevent PDF range browser cache serialization

feat: support additional Reader formats

Optimize long PDF Reader performance

feat: search PDFs from strict v2 text indexes

Complete Reader recovery and static asset updates