chore: rename k9 directories to self-validating for clarity

hyperpolymath committed Jun 21, 2026

wiki: add six topic guides for outside readers Add Linear-and-affine, Region-calculus, Two-phase-compiler, What-can-go-wrong, Comparison-to-other-languages, and Glossary. Each opens with a 1-paragraph what/why/where summary, cross-links the others, and references concrete files in the ephapax repo. Update _Sidebar.md with a "Topic guides" section. Proof-state claims stay consistent with Proof-status.md: preservation is 22 open / 910 closed; the Idris2 frontend is 8/9 files %default total + 1 %default covering.

hyperpolymath committed May 20, 2026