Add static class names to UI elements for easier customization (#4421)

* Initial plan

* Add static class names to UI elements for easier customization

Co-authored-by: gabek <414923+gabek@users.noreply.github.com>

* Add unique DOM element IDs for easier customization targeting

Co-authored-by: gabek <414923+gabek@users.noreply.github.com>

* Remove duplicate class names, keep only IDs for UI element targeting

Co-authored-by: gabek <414923+gabek@users.noreply.github.com>

* Revert chat input field ID to original value

Co-authored-by: gabek <414923+gabek@users.noreply.github.com>

* Remove unnecessary nested spans and revert Button ID to original value

Co-authored-by: gabek <414923+gabek@users.noreply.github.com>

* Standardize ID names to follow owncast-{element-description}-{type} pattern

Co-authored-by: gabek <414923+gabek@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: gabek <414923+gabek@users.noreply.github.com>
Co-authored-by: Gabe Kangas <gabek@real-ity.com>

web/components/ui/Footer/Footer.tsx

@@ -13,7 +13,7 @@ export const Footer: FC = () => {
   const { t } = useTranslation();
   return (
     <footer className={styles.footer} id="footer">
-      <span>
+      <span id="owncast-powered-by-text">
         <Translation
           translationKey={Localization.Common.poweredByOwncastVersion}
           vars={{ versionNumber }}