ccgui 0.6.3 பதிவிறக்கம்

New Features
- add vercel-optimize and writing-guidelines agent skills
- persist per-engine composer preferences
- add builtin claude model catalog with override precedence
- rework context usage indicator with ai-elements style
Fixes
- remeasure mounted rows instead of wiping virtualizer size cache
Performance Improvements
- pause background polling and cut idle render storms
- eliminate O(L^2) streaming merge and keep heavy vendors lazy
- stop heavy subtrees re-rendering on every app-shell root render
- move composer state out of app-shell root and tame render storms