Pin nightly release host JDK to 27.0.0 (#2515)

The nightly release build fails in the :jre task because setup-java now
resolves java-version '27' to Liberica 27.0.1, while runtimeZipOthers and
runtimeZipWindows download 27+36 (27.0.0) target JDKs. jlink requires the
target java.base version to exactly match its own version, so it exits 1.

Pin the host JDK to 27.0.0 so it matches the downloaded JDKs. Bump both
together when updating jdk_download_base in build.gradle.


Claude-Session: https://claude.ai/code/session_01TNQURTPv1or2s6qjnk4NMB

Co-authored-by: Dennis Sheirer <dennis.sheirer@gmail.com>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

.github/workflows/nightly.yml

@@ -18,7 +18,8 @@ jobs:
       - name: Set up JDK 27
         uses: actions/setup-java@v3
         with:
-          java-version: '27'
+          # Must match the JDK version downloaded in build.gradle (jdk_download_base) - jlink requires an exact version match
+          java-version: '27.0.0'
           distribution: 'liberica'
           java-package: 'jdk+fx'