feat(installer): self-select release download source (#176)

.github/workflows/release.yml

@@ -111,14 +111,36 @@ jobs:
         run: pnpm install --frozen-lockfile
 
       # Inject the release tag into core's VERSION constant (the source for CLI --version and the install-complete
-      # message); otherwise artifacts always carry the in-repo dev version and multiple installs can't be told apart.
-      # BUILD_DATE is stamped alongside it with this run's UTC date (the repo keeps null for dev builds).
+      # message) and both standalone installers. The stamped installers then select the same immutable OSS/GitHub
+      # release when run directly. BUILD_DATE is stamped alongside core with this run's UTC date.
       - name: Stamp release version
         run: |
           TAG="${{ github.event_name == 'workflow_dispatch' && inputs.tag || github.ref_name }}"
           V="${TAG#v}"
+          printf '%s\n' "$TAG" | grep -Eq '^v[0-9A-Za-z][0-9A-Za-z._-]*$'
           grep -q 'export const VERSION = "' packages/core/src/index.ts
           sed -i "s/export const VERSION = \"[^\"]*\"/export const VERSION = \"$V\"/" packages/core/src/index.ts
+          SH_MARKER='EMBEDDED_RELEASE_VERSION="__PENGUIN_RELEASE_VERSION__"'
+          PS_MARKER='$EmbeddedReleaseVersion = "__PENGUIN_RELEASE_VERSION__"'
+          if grep -Fq "$SH_MARKER" install.sh; then SH_HAS_MARKER=1; else SH_HAS_MARKER=0; fi
+          if grep -Fq "$PS_MARKER" install.ps1; then PS_HAS_MARKER=1; else PS_HAS_MARKER=0; fi
+          case "$SH_HAS_MARKER:$PS_HAS_MARKER" in
+            1:1)
+              sed -i "s/__PENGUIN_RELEASE_VERSION__/$TAG/g" install.sh
+              sed -i "s/__PENGUIN_RELEASE_VERSION__/$TAG/g" install.ps1
+              grep -Fq "EMBEDDED_RELEASE_VERSION=\"$TAG\"" install.sh
+              grep -Fq "\$EmbeddedReleaseVersion = \"$TAG\"" install.ps1
+              ;;
+            0:0)
+              # Tags created before installer version stamping have neither marker. Preserve their
+              # historical installers so a missing Release can still be rebuilt from the tag source.
+              echo "Legacy tag without embedded installer versions; leaving installers unstamped."
+              ;;
+            *)
+              echo "Installer release-version markers are inconsistent." >&2
+              exit 1
+              ;;
+          esac
           D="$(date -u +%Y-%m-%d)"
           # BRE: the unescaped | in these patterns is literal (grep/sed default to POSIX BRE, where | is not alternation).
           grep -q 'export const BUILD_DATE: string | null = ' packages/core/src/index.ts