feat(library): add platform badges, remove hide duplicates

Gitea #34 slice 2 of 3. Core lists each set once now.
The hide duplicates toggle and its param are not needed.
PlatformIcons shows a badge per platform (platforms[]).

README.md

@@ -55,12 +55,14 @@ To Be Played is split into three repositories:
   system setting "reduce motion" or the "Reduce animations" switch in the settings.
 - **Landing page**: next to the community numbers and the top games, three blocks: games per platform, top genres and
   finished games per year of all users.
-- **Library**: status filters, source filter (Steam, PlayStation, manual; a linked set counts on each of its sources), "short games" filter (up to 10 h), search, sorting by playtime, recently seen, newest
-  in library, rating or priority, paging. Each row shows the unlocked achievements.
+- **Library**: status filters, source filter (Steam, PlayStation, manual; a linked set matches on each of its sources), "short games" filter (up to 10 h), search, sorting by playtime, recently seen, newest
+  in library, rating or priority, paging. Each row shows the unlocked achievements. A game you own on several
+  platforms is one row (Core's counted edition) with a small badge per platform next to the title (`PlatformIcons`:
+  ST, PS or the platform name, from `platforms[]`; lucide has no brand icons).
 - **Editions**: the editions of one game (Steam and PS5 copy, remaster, port) are linked automatically from IGDB's
   "same game" key; an auditor can also link or unlink them for every user. A user who owns two or more of a linked
-  set sees "Also in your library" on the details page, an "x2" badge in the library and the filter "Hide
-  duplicates"; the numbers count the set once. The editions of a set share one status, rating and notes (the page
+  set sees "Also in your library" on the details page and an "x2" badge in the library; the library lists the set
+  once (no "Hide duplicates" filter any more), and the numbers count it once. The editions of a set share one status, rating and notes (the page
   reloads after a save to show it). "Not the same game" splits the game off its set for this user only, and it stays
   split. "Same game as..." on the details page asks the auditors for a link.
 - **Add a game by name** for games outside Steam (PlayStation, Switch, Xbox, physical): search IGDB, pick a hit,
@@ -259,6 +261,13 @@ flowchart LR
   which question is open; `src/utils/questions.js` only loads the list and sends the answer. A yes to Finished? gets
   the Rate it? card back at once. `409` / `404` reload the list. `RatingStars` is shared with `BacklogCard`.
 
+```mermaid
+flowchart LR
+    Games["Core GET /api/library/games: one row per set + platforms[]"] --> Row["GameLibrary row"]
+    Row --> Icons["PlatformIcons: badge per platform"]
+    Row -.->|"no platforms (hidden game)"| Badge["single platform badge"]
+```
+
 ```mermaid
 flowchart LR
     Detail["GameDetail: EditionsCard"] -->|"Not the same game"| Split["Core DELETE /api/library/games/{appid}/set"]