docs(mobile): update README for post creation and comments

mobile/README.md

@@ -161,6 +161,9 @@ mobile/
         notifications.tsx   # notifications list
         pets.tsx             # owner's pets + active-pet switcher
       messages/index.tsx    # conversations list
+      post-new.tsx           # create a photo post (pick/upload → posts.create)
+      posts/[postId]/comments.tsx  # read/write/delete comments for a post
+      image-viewer.tsx        # full-screen tapped-image lightbox
   src/
     api/trpc.ts             # tRPC client, AppRouter type import, query client factory
     api/types.ts             # inferRouterOutputs<AppRouter> shortcuts (Pet, FeedPost, ...)
@@ -171,6 +174,7 @@ mobile/
     lib/media-url.ts          # Supabase public storage URL builder
     lib/format.ts             # pet display name + relative-time formatting
     lib/sponsor.ts             # active-sponsor check
+    lib/upload.ts              # direct PUT of a picked image to a presigned Supabase URL
     theme/tokens.ts            # design tokens mirroring the web app's DESIGN.md
     components/                 # Button, TextField, Card, PostCard, PawButton, PetAvatar, PetIdentityBadges
 ```
@@ -195,13 +199,10 @@ separately. "Starting with Android" means:
 
 Phase 1 (Feed/Explore/Notifications/Pets tabs, reactions, active-pet
 switching, persisted cache for fast reopen) plus a full pet profile
-(view/follow/edit/followers-following) are done and verified end-to-end
-against the live backend on a real Android emulator. Still missing, roughly
-in the order they'd unblock the most:
+(view/follow/edit/followers-following), post creation/upload, and comments
+are done and verified end-to-end against the live backend on a real Android
+emulator. Still missing, roughly in the order they'd unblock the most:
 
-- Post creation/upload (camera/gallery → Supabase direct upload, per
-  `posts.getPresignedUrl`/`posts.create`)
-- Comments (reading + posting — `PostDetailDialog` equivalent)
 - Repost creation (the count already renders, creating one doesn't)
 - Stories (story ring, viewer, creation)
 - Video playback (currently a static placeholder for `type === "VIDEO"` posts)