Fix CI: install cmake/curl/python3, not just bison

The CI runner's base image doesn't ship cmake (build failed with
"cmake executable not found on PATH" during emcmake), and only bison
was ever explicitly installed - curl and python3 happened to work by
luck of the current runner image, not because the workflow guarantees
them. Install the full README-documented toolchain explicitly in both
the build and publish jobs.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.gitea/workflows/ci.yml

@@ -11,10 +11,10 @@ jobs:
     steps:
       - uses: https://github.com/actions/checkout@v4
 
-      - name: Install bison
+      - name: Install build dependencies
         run: |
           sudo apt-get update
-          sudo apt-get install -y bison
+          sudo apt-get install -y bison cmake curl python3
 
       - name: Cache emsdk
         uses: https://github.com/actions/cache@v4
@@ -72,10 +72,10 @@ jobs:
     steps:
       - uses: https://github.com/actions/checkout@v4
 
-      - name: Install bison
+      - name: Install build dependencies
         run: |
           sudo apt-get update
-          sudo apt-get install -y bison
+          sudo apt-get install -y bison cmake curl python3
 
       - name: Cache emsdk
         uses: https://github.com/actions/cache@v4