Steps to take before GA

Before releasing this extension, there are a few steps to verify:

- [ ] **Update the location of the Prompt API.** Currently we use `chrome.aiOriginTrial.languageModel`, and that's certainly not the final destination of the API. This should be updated in `summarizers.js`.
- [ ] **Verify the location of the Summarizer API.** It seems like it may stay at `globalThis.Summarizer`, and it should be verified before GA.
- [ ] **Add confirmation to clip deletion.** Right now, clicking on the delete icon immediately deletes the clip. It would be good to add a confirmation step so people don't accidentally delete clips.