ui: remove click-to-play overlay; native play button covers autoplay-block

SPEC.md

@@ -86,8 +86,8 @@ Flow: search box → results grid (poster + title, click) → detail view
 
 - Default play: opening an anime resumes the last watched episode of
   the season (seeking to the saved position unless ≥95% through),
-  else autoplays episode 1. If the browser blocks autoplay, a
-  "click to play" overlay appears.
+  else autoplays episode 1. If the browser blocks autoplay, the native
+  play button on the video is the way to start.
 - Watch position saved to `/api/history` every ~10s + on pause/unload;
   home page lists the 5 most recent entries with timecode.