docs(readme,landing): introduce the desktop app (#201)

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

.github/workflows/desktop-build.yml

@@ -75,8 +75,8 @@ jobs:
           name: desktop-${{ runner.os }}
           if-no-files-found: error
           path: |
-            packages/desktop/stage/out/*.AppImage
-            packages/desktop/stage/out/*.deb
-            packages/desktop/stage/out/*.dmg
-            packages/desktop/stage/out/*-mac.zip
-            packages/desktop/stage/out/*.exe
+            packages/desktop/stage/out/penguin-desktop-*.AppImage
+            packages/desktop/stage/out/penguin-desktop-*.deb
+            packages/desktop/stage/out/penguin-desktop-*.dmg
+            packages/desktop/stage/out/penguin-desktop-*.zip
+            packages/desktop/stage/out/penguin-desktop-*.exe

.github/workflows/release.yml

@@ -316,8 +316,8 @@ jobs:
 
       # Desktop installers built by the desktop job (three-OS matrix): collected here so
       # they are part of the Release's initial (immutable) asset set. Their checksums go
-      # in a separate SHA256SUMS.desktop — the OSS mirror script's canonical file list
-      # stays untouched (desktop installers are not mirrored yet).
+      # in a separate SHA256SUMS.desktop, which is also how the OSS mirror script verifies
+      # them (its manifest lists the installers by their version-less names).
       - name: Collect desktop artifacts
         uses: actions/download-artifact@v4
         with: