Assign retained TP identity before layout and emit pure, runtime-free surface plans with exact character and text-property equivalence. Keep live publication unchanged for the staged cutover and add focused surface, package, docs, and CI contracts.\n\nVerified: make check EMACS=/Applications/Emacs.app/Contents/MacOS/Emacs\nVerified: WERROR byte compilation for all 16 active Lisp files\nVerified: focused ebox-surface checkdoc has zero warnings
Keep the standalone Ebox package focused on its public layout and DSL primitives while the generic ebox-playground package owns executable .ebox references.
Split the verified renderer, layout engine, Grid support, native boundary, tests, examples, and paired documentation into the independent Ebox repository. Keep ETAF and application concerns outside this package.
