Improved fetch and scrape workflow (with new UI on background tabs)

You should see a higher success rate of summaries going through.

YouTube pushed a UI update that broke transcript fetching, so this release fixes that first. Beyond that, a bunch of quality of life stuff I wanted to add for a while.

There's now a full settings screen inside the widget itself. Click the gear icon on any summary, or click the button before summarizing anything, and it opens up. From there you can manage your API keys, edit the prompt, and change visual preferences without leaving the page.

You can now pick where the button lives on screen. Six positions to choose from, corners and edges. There's also a translucency and blur slider so you can make the background see-through without affecting the text readability.

In fullscreen mode the button now automatically repositions itself so it's not sitting on top of the player controls, and there's a small X button to hide it entirely if you want. It comes back when you exit fullscreen.

Last thing: the button on the home feed was showing up as a full-width bar under each video which looked bad. It's a small pill now, same as everywhere else.