Close out installer/AppImage verification; note v0.2.1 release; document NSIS/appstream gotchas

- CI run 1110 proved NSIS + AppImage packaging and published v0.2.1
  (installers uploaded); Mark TODO installer/appimage items done (moved to
  DONE.md), README Latest -> v0.2.1, MEMORY records NSIS -D/absolute-path/
  BMP-ICO gotchas and appstreamcli strictness

DONE.md

@@ -173,6 +173,10 @@ Completed task sections moved from `TODO.md`. Sections are moved only when every
 - [x] `config/version` → `0.2.0`; `build/` artifacts rebuilt and Linux binary smoke-tested.
 - [x] New world/lighting headless tests (56 total).
 
+## Screenshot Refresh
+
+- [x] Regenerate and verify the six README screenshots from the current build.
+
 ## 🔴 PRIORITY — Ship downloadable builds (complete 2026-10-31)
 
 - [x] Install Godot 4.3 export templates locally.
@@ -216,7 +220,13 @@ Completed task sections moved from `TODO.md`. Sections are moved only when every
       ran it headless (0 script errors).
 - [x] CI: NSIS + AppImage steps added to `.gitea/workflows/build.yml` build job; publish glob
       already uploads `build/step-line-*<ver>*` (covers setup/AppImage names).
-- [ ] (open) CI run verification of the NSIS build and installer-content listing.
+- [x] CI run 1110 verified end-to-end (v0.2.1): NSIS installer `step-line-setup-0.2.1.exe`
+      built, `7z l` shows `step-line.exe` + `uninstall.exe`, AppImage built (33.9 MB),
+      release `v0.2.1` published, `Job succeeded`.
+  - Gotchas fixed on the way: makensis needs `-D` defines (not `/D`) and absolute paths
+    (it resolves relatives against the script dir); installed exe must be space-free
+    (`step-line.exe`); icon.ico must use classic BMP entries (ImageMagick; PIL emits
+    PNG-compressed ICOs NSIS rejects).
 
 ## 🎮 Assets & detailed graphics pass (textures, rigs, UI feedback)