ci: pin @antora/pdf-extension to 1.0.0-beta.20

@antora/pdf-extension@1.0.0-rc.1 (published 2026-06-29) bundles
@antora/assembler@1.0.0-rc.1, which calls contentCatalog.createFile() — a
method absent from @antora/content-classifier@3.1.10 used by the pinned
antora@3.1.7. The unpinned install began resolving to rc.1, causing
'FATAL (antora): contentCatalog.createFile is not a function'.

Pin to the last-known-good 1.0.0-beta.20 to restore the working toolchain.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: hs-liuxh

.github/workflows/merge-build-push.yml

@@ -192,7 +192,7 @@ jobs:
       - name: Install Antora CLI
         run: |
           echo "Installing Antora packages local..."
-          npm install --global antora@3.1.7  @antora/lunr-extension  @antora/pdf-extension  @node-rs/jieba
+          npm install --global antora@3.1.7  @antora/lunr-extension  @antora/pdf-extension@1.0.0-beta.20  @node-rs/jieba
 
       - name: Build English Documentation
         working-directory: ./ivory-doc-builder

.github/workflows/pr-preview.yml

@@ -107,7 +107,7 @@ jobs:
       - name: Install Antora CLI
         run: |
           echo "Installing Antora packages local..."
-          npm install --global antora@3.1.7  @antora/lunr-extension  @antora/pdf-extension  @node-rs/jieba
+          npm install --global antora@3.1.7  @antora/lunr-extension  @antora/pdf-extension@1.0.0-beta.20  @node-rs/jieba
 
       - name: Build English Documentation
         working-directory: ./ivory-doc-builder