feat(installer): add deno sync-types subcommand
Move the stock-TypeScript config generation out of the implicit deno install
path into an explicit `deno sync-types` subcommand. It materializes jsr: and
http(s): types and writes a tsconfig.json + .deno/tsconfig.json so stock TS
tooling (tsc, tsgo, editors) can type-check a Deno project. Run after
installing dependencies.
