Strip HTML comments from RSS feed descriptions

### Description

HTML comments (e.g., ``, ``) sometimes appear in RSS feed descriptions, making them visible to users in the RSS widget.

In `internal/glance/widget-rss.go`, add a regex pattern to strip HTML comments in `sanitizeFeedDescription()`:
```go
var htmlCommentsPattern = regexp.MustCompile(``)
```

I'd like to submit a PR for this if the approach looks good.

Start in internal/glance/widget-rss.go and read sanitizeFeedDescription() along with the surrounding RSS description handling. Add the requested HTML-comment removal there, then verify that RSS descriptions no longer expose comments such as or while preserving the remaining description content.

Written by the indexing model from the issue text.