docs: settle the export docs on the final delivery matrix

ARCHITECTURE: the time zone rides the URL too; 'only degraded platform'
(legacy TG) instead of 'only remaining branch' — the delivery is
per-platform by design now. CLAUDE.md: the renderer joins the build/test
commands and the Dockerfile list.

docs/ARCHITECTURE.md

@@ -813,12 +813,12 @@ authenticated caller on a finished game. The PNG is rasterized on demand by the
 **`renderer` sidecar** (internal-only Node + skia-canvas running the same
 `ui/src/lib/gameimage.ts` the web project unit-tests — one renderer, no drift;
 `renderer/README.md`); the backend rebuilds the render payload from the journal +
-`engine.AlphabetTable`, and the client's date locale plus its UI-localized non-play
-labels ride the signed URL so the server render matches the player's presentation.
-Nothing is stored: the artifact is re-derived from the immutable finished journal on
-each GET. The only remaining platform branch is a legacy Telegram client predating
-`downloadFile`, where the GCG falls back to the old clipboard copy and the image option
-is not offered.
+`engine.AlphabetTable`, and the client's date locale, IANA time zone and UI-localized
+non-play labels ride the signed URL so the server render matches the player's
+presentation. Nothing is stored: the artifact is re-derived from the immutable
+finished journal on each GET. The only degraded platform is a legacy Telegram client
+predating `downloadFile`, where the GCG falls back to the old clipboard copy and the
+image option is not offered.
 
 The alphabet-on-the-wire transport does **not** touch this invariant: the live edge
 exchanges alphabet indices, but the persisted journal (and everything derived from it —