feat: various changes #131

CHANGELOG.md

devenv.lock

package.json

playground/context-help/index.html

playground/context-help/main.js

playground/context-help/main.pcss

playground/datatable/data.json

playground/datatable/index.html

playground/datatable/main.js

playground/select/data.json

playground/select/data2.json

playground/select/index.html

playground/select/main.js

pnpm-lock.yaml

source/components/datatable/datasource/rest.mjs

source/components/datatable/datatable.mjs

source/components/datatable/datatable/header.mjs

source/components/datatable/embedded-pagination.mjs

source/components/datatable/filter.mjs

source/components/datatable/filter/util.mjs