jekyll: move jekyll back to root, but simpler setup, exclude via _config.yml

app: bundle jekyll docs into app, add 'yarn run docs' to build
ui: add back/forward arrows for app only, adjust responsiveness for app, add IS_APP flag injected via preload
ui: add animated logo, friendly message on empty replay frame
app: improve serve logic:
- serve static files from static root
- serve replay from http localhost instead to avoid proxying https for remote requests
- serve local lookup from http prefix also
- catch any fallthrough from replay as 404
- add timestamp to response channels to ensure uniqness

.gitignore

@@ -1,12 +1,12 @@
 *.har
 *.warc
 *.warc.gz
-!docs/examples/*.warc
+!examples/*.warc
 **/node_modules
 yarn-error.log
 coverage/
 **/local-examples/
 **/.DS_Store
 **/.sass-cache/
-docs/_site/
+_site/
 dist/