- composition.md: add text backdrop (gaussian dark mask behind glyphs) and
external layout oracle pattern (browser-based text layout → JSON → Python
renderer pipeline for obstacle-aware text reflow)
- shaders.md: add reverse vignette shader (center-darkening for text readability)
- troubleshooting.md: add diagnostic entries for text-over-busy-background
readability and kaleidoscope-destroys-text pitfall
ab62614a89