Adds the `flat-square` style to action badges. Styles can be selected by
adding `?style=<style>` to the badge endpoint. If no style query is
given, or if the query is invalid, the style defaults to `flat`.
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Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
This PR only does "renaming":
* `Route` should be `Router` (and chi router is also called "router")
* `Params` should be `PathParam` (to distingush it from URL query param, and to match `FormString`)
* Use lower case for private functions to avoid exposing or abusing