examples: browser playground (TS-flavored UI + Go backend) (#72)

Merge branch 'main' into cmd-repl

docs: replace Features with a Protocol support matrix (original -> Go)

Add missing doc comment on ErrorExpr.Error

Fix go vet: check http.Post error before using resp

Resolve merge conflicts

Fix interop: wrap method path as array in call expressions

Implement import/export tables with reference counting

Add fuzz tests for DecodeExpr, fix whitespace-prefix bug