escriba-ts — tree-sitter multi-grammar host.
Phase-1.B scope: one GrammarRegistry keyed by language-name string,
shipped with tree-sitter-rust; per-buffer BufferParser that keeps a
tree_sitter::Tree and re-parses on edits. Highlight capture via
tree_sitter_highlight::HighlightConfiguration → Semantic bindings
from caixa_theme. Phase 2: caixa-ts grammar + markdown + bash + incremental
Tree::edit() per Edit.