docs: clarify that the architecture evolves, not the model

docs: reframe Cog as convention-based learning tool with Unix-native design

feat(pipeline): add Unix toolbox orientation to pipeline skills

feat: comprehensive pipeline skill upgrades from PAI learnings

feat: scalable entities & patterns architecture

fix: update L0 convention — line 1, not after title

chore(memory): L0 line-1 convention — all files start with L0 summary

feat: initial cog release — cognitive architecture for Claude Code