Add event text to full-screen Carousel view

The full screen carousel looks quite empty. When viewing videos, it
looks like the video is being played full screen, when it is really not.

Alas, SwiftUI/UIKit does not provide an API for programmatically
bringing a video player full screen. The closest we can do is show the
system native playback controls.

This can cause confusion to users, and is not the best UX. To get around
these limitations and improve UX, event information and content is added to the full
screen carousel overlay, so that:

- Users can see a piece of the post while they are browsing images and videos
- Users can more clearly tell when the video is being displayed on the full screen carousel or on full screen
- Users have a way to directly go to the thread view within the full screen carousel

Changelog-Added: Add event content preview to the full screen carousel
Signed-off-by: Daniel D’Aquino <daniel@daquino.me>
Link: 20240318222048.14226-4-daniel@daquino.me
Signed-off-by: William Casarin <jb55@jb55.com>

damus/Components/TruncatedText.swift

@@ -9,7 +9,12 @@ import SwiftUI
 
 struct TruncatedText: View {
     let text: CompatibleText
-    let maxChars: Int = 280
+    let maxChars: Int
+    
+    init(text: CompatibleText, maxChars: Int = 280) {
+        self.text = text
+        self.maxChars = maxChars
+    }
     
     var body: some View {
         let truncatedAttributedString: AttributedString? = text.attributed.truncateOrNil(maxLength: maxChars)