Add an edit/delete manage screen to the Android app

A new Manage screen (reached from the Post screen) lists published posts with
thumbnails and lets you edit a post's caption, date and tags or delete it to the
server's trash, over the same /api/photos, /api/edit and /api/delete endpoints
the web /manage uses.

UploadClient gains listPhotos/editPost/deletePost/fetchThumbnail, parsing JSON
with the built-in org.json (no new dependency) and posting edits/deletes as
urlencoded forms. The app sends no Origin or Sec-Fetch-Site header, so it passes
the server's same-origin CSRF check as a non-browser client; Basic auth is
already attached on every request. UploadViewModel holds the manage state,
loads the list, fetches thumbnails in the background, and applies edits/deletes
optimistically.

CLAUDE.md

@@ -189,7 +189,7 @@ go run . --serve
 
 ## Android app
 
-Kotlin + Jetpack Compose uploader: pick or share a photo, add caption and date, post. Credentials (HTTP Basic) are sealed with an Android Keystore AES-GCM key. See `android/README.md` for the detail.
+Kotlin + Jetpack Compose uploader: pick or share one or many photos, add caption/date/tags, post via a durable WorkManager queue. It also has a **Manage screen** (from the Post screen's "Manage" button) that lists published posts with thumbnails and edits caption/date/tags or deletes (to trash) via the same `/api/photos`, `/api/edit`, `/api/delete` endpoints the web `/manage` uses. The manage calls go through `UploadClient` (OkHttp + `org.json`, no extra deps); sending no `Origin`/`Sec-Fetch-Site` header, the app passes the server's same-origin CSRF check as a non-browser client. Credentials (HTTP Basic) are sealed with an Android Keystore AES-GCM key. See `android/README.md` for the detail.
 
 Its own flake, deliberately separate from the root one so NixOS consumers of `nixosModules.default` don't pull the Android SDK into their lock:
 
@@ -262,7 +262,7 @@ nix build          # succeeds
 ## What's not done yet
 
 - ActivityPub federation (planned later — start with RSS/Atom)
-- Edit/delete/trash in the Android and Qt apps (web `/manage` only so far; the `/api/` endpoints are there for the apps to adopt)
+- Edit/delete in the **Qt desktop** app (web `/manage` and the Android app have it; the `/api/` endpoints are there for Qt to adopt). Restoring from trash is still web-only on all clients.
 - Any auth beyond the app's htpasswd Basic auth (no sessions, no per-user scopes)
 - The Android app has never been run on real hardware
 - Photo-page swipe has never been tested on a real touchscreen; the iOS Safari edge-gesture interaction is the untested part