fix(home): drop letterbox band on deck example-prompt previews (#5105)

The baked deck preview (od.bakedPreview) is captured at the 1.31 tile
aspect, so a deck's fixed 16:9 stage self-letterboxes with a dark
--stage-bg band baked into the poster/clip. The existing data-od-mode
override only reframes the LIVE iframe surface, but the Home
example-prompt tiles render the BAKED media (preferBaked) — which was
object-fit:cover'd and top-anchored, so the top letterbox band showed as
a black strip above every deck slide.

Mirror the iframe deck treatment for the baked media: render the clip in
a native 16:9 box centered in the standard cell and center-crop it, so
cover() strips exactly the baked letterbox and the slide reads
edge-to-edge with no dark band. Non-deck tiles keep the top-anchored 1.31
clip so web-page hero headlines stay in frame.

Author: lefarcen

apps/web/src/styles/home/home-hero.css

@@ -2398,6 +2398,32 @@
   transform: none;
 }
 
+/* The baked deck preview (od.bakedPreview) is captured at the 1.31 tile aspect,
+   so the deck's fixed 16:9 stage self-letterboxes with a dark --stage-bg band
+   baked into the poster/clip. The iframe rule above only fixes the LIVE surface;
+   these preset tiles render the BAKED media (preferBaked), so mirror the same
+   treatment for it: render the clip in a native 16:9 box centered in the
+   standard cell and center-crop it, so object-fit:cover strips exactly the baked
+   letterbox and the slide reads edge-to-edge with no dark band. (Non-deck tiles
+   keep the top-anchored 1.31 clip below so web-page hero headlines stay in
+   frame.) */
+.home-hero__plugin-preset[data-od-mode="deck"] .plugins-home__preview--media {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+}
+.home-hero__plugin-preset[data-od-mode="deck"] .plugins-home__media {
+  position: relative;
+  inset: auto;
+  width: 100%;
+  height: auto;
+  aspect-ratio: 16 / 9;
+}
+.home-hero__plugin-preset[data-od-mode="deck"] .plugins-home__media-img,
+.home-hero__plugin-preset[data-od-mode="deck"] .plugins-home__media-video {
+  object-position: center;
+}
+
 /* Baked clips are framed 1.31:1 for the Community grid; the wider preset tiles
    would otherwise object-fit:cover-crop the hero out of the middle. Anchor to
    the top so the hero headline stays in frame. Scoped to the preset cards. */