fix(media): rework portrait image sizing to fill+object-contain

Chasing this through width/height class combinations (w-fit/h-fit vs
w-auto/h-auto) kept trading one bug for another: centering broke height,
fixing height broke centering. Root cause: max-h-full/max-w-full on the
image are percentages, and every wrapper in the chain only ever had an
intrinsic (auto/fit-content) size — CSS treats percentages against an
intrinsically-sized parent as unresolvable, so which axis "won" depended
on incidental flex-stretch behavior rather than anything deliberate.

Replaced the shrink-wrap-to-image approach with fill-the-definite-parent:
wrapper and image now take w-full h-full of the already definitely-sized
media column (PostDetailDialog) / full-screen overlay (StoryViewer), and
object-contain (default centered) handles aspect-ratio scaling entirely
on its own — no percentage resolution against an ambiguous parent left
anywhere in the chain.

Not visually verified locally (auth-gated route) — needs a real check
against a portrait post/story after deploy.

src/components/feed/PostDetailDialog.tsx

@@ -243,6 +243,14 @@ export function PostDetailDialog({ post, open, onClose, onDeleted }: PostDetailD
     </>
   );
 
+  // Image wrappers below fill the (definitely-sized) media column and let
+  // object-contain handle aspect-ratio scaling/centering. An earlier
+  // "shrink-wrap to the image's own rendered box" approach relied on
+  // percentage max-height/max-width resolving against an intrinsically-sized
+  // (auto/fit-content) parent, which CSS treats as unresolvable — portrait
+  // images ended up either uncentered or rendered at full natural size
+  // (clipped) depending on which axis lost. Filling a definite-size parent
+  // avoids that class of bug entirely.
   const mediaContent = post.type === "VIDEO" && post.videoPost ? (
     <div className="relative h-full w-full">
       <VideoCard
@@ -259,13 +267,13 @@ export function PostDetailDialog({ post, open, onClose, onDeleted }: PostDetailD
         <Carousel setApi={setCarouselApi} className="h-full">
           <CarouselContent className="h-full">
             {images.map((img) => (
-              <CarouselItem key={img.id} className="basis-full flex items-center justify-center h-full">
+              <CarouselItem key={img.id} className="basis-full h-full">
                 <BlurImage
                   src={getMediaUrl(img.storageKey) ?? ""}
                   blurhash={img.blurhash}
                   alt={currentCaption ?? `${pet.name}'s post`}
-                  className="block max-h-full max-w-full object-contain"
-                  wrapperClassName="relative block h-auto w-fit"
+                  className="block w-full h-full object-contain"
+                  wrapperClassName="relative block w-full h-full"
                 />
               </CarouselItem>
             ))}
@@ -288,13 +296,13 @@ export function PostDetailDialog({ post, open, onClose, onDeleted }: PostDetailD
         </div>
       </div>
     ) : (
-      <div className="relative inline-flex w-fit max-h-full max-w-full">
+      <div className="relative w-full h-full">
         <BlurImage
           src={getMediaUrl(images[0].storageKey) ?? ""}
           blurhash={images[0].blurhash}
           alt={currentCaption ?? `${pet.name}'s post`}
-          className="block max-h-full max-w-full object-contain"
-          wrapperClassName="relative block h-auto w-fit"
+          className="block w-full h-full object-contain"
+          wrapperClassName="relative block w-full h-full"
         />
         <AiDisclosureBadge value={post.aiDisclosure} className="h-8" />
       </div>

src/components/stories/StoryViewer.tsx

@@ -155,20 +155,23 @@ export function StoryViewer({
             ))}
           </div>
 
-          {/* Story image — inline-flex wrapper shrinks to the actual rendered
-              image box (not the full-screen overlay) so both the centering
-              and the badge overlay track the real image bounds. BlurImage's
-              own wrapper defaults to w-full/h-full (fine for fill-container
-              usages like feed thumbnails), so it's overridden here via
-              wrapperClassName. */}
+          {/* Story image — wrapper fills the full-screen overlay and
+              object-contain does all the aspect-ratio scaling/centering
+              itself. A previous "shrink-wrap to the image's own rendered
+              box" approach relied on percentage max-height/max-width
+              resolving against an intrinsically-sized (auto/fit-content)
+              parent, which CSS treats as unresolvable — portrait images
+              would render at full natural size (clipped) or lose centering
+              depending on which axis' ambiguity won. Filling a definite-size
+              parent sidesteps that class of bug entirely. */}
           {mediaUrl && (
-            <div className="relative inline-flex w-fit max-h-screen max-w-full">
+            <div className="relative w-full h-full">
               <BlurImage
                 src={mediaUrl}
                 blurhash={currentStory.blurhash}
                 alt={t("storyAriaLabel", { petName })}
-                className="block max-h-screen max-w-full object-contain"
-                wrapperClassName="relative block h-auto w-fit"
+                className="block w-full h-full object-contain"
+                wrapperClassName="relative block w-full h-full"
               />
               <AiDisclosureBadge
                 value={currentStory.aiDisclosure}