Site reorg: Remove site/ subpath (#306)

Unfortunately, for proper package pathing, need to remove the `site/`
subpath. This includes:
- Moving everything back into root
- Adding a `copy-site.sh` script to copy resources into `mkdocs/site/`
before building the site with mkdocs.
- Also update examples to ensure all are loading the local sw.js / ui.js
- Consolidate examples in `docs/examples`
- Consolidate assets under src/assets/
- Move `favicons` to root
- Reformat and relint
- Tests: update playwright tests to use mkdocs output, add test for
embed in docs
- bump to 2.0.0-beta.2

src/embed.ts

@@ -118,8 +118,6 @@ class Embed extends LitElement {
       await this.swmanager.register();
       this.inited = true;
     } catch (e) {
-      // TODO: Fix this the next time the file is edited.
-      // eslint-disable-next-line @typescript-eslint/no-unsafe-argument
       this.errorMessage = this.swmanager.renderErrorReport();
     }
   }