ci(tst-03): provision pwsh + gradle for the self-hosted act runner

The portable and java jobs assumed tools GitHub-hosted runners preinstall but the
self-hosted catthehacker act image lacks: `pwsh` (the codegen freshness check uses
`shell: pwsh`) and `gradle` (the java job runs `gradle test`; the repo has no
wrapper). Install PowerShell as a .NET global tool (the SDK is already set up) and
provision gradle via gradle/actions/setup-gradle. No behavior change on
GitHub-hosted runners, which already have both.

Claude-Session: https://claude.ai/code/session_01DMXXvNuPekkkrTEyPNxEkW

.gitea/workflows/ci.yml

@@ -49,6 +49,13 @@ jobs:
       - name: Build NonWindows solution
         run: dotnet build src/ZB.MOM.WW.MxGateway.NonWindows.slnx -c Release
 
+      # GitHub-hosted runners ship pwsh; the self-hosted act image does not. Install it as a
+      # .NET global tool (the SDK is already set up above) so the codegen check's `shell: pwsh` works.
+      - name: Install PowerShell (pwsh)
+        run: |
+          dotnet tool install --global PowerShell
+          echo "$HOME/.dotnet/tools" >> "$GITHUB_PATH"
+
       # IPC-01 / IPC-19 / IPC-20: descriptor set + Contracts/Generated must match the current protos.
       - name: Codegen / descriptor freshness
         shell: pwsh
@@ -93,6 +100,11 @@ jobs:
         with:
           distribution: temurin
           java-version: '17'
+      # GitHub-hosted runners ship gradle on PATH; the self-hosted act image does not, and the repo
+      # has no gradle wrapper. Provision gradle (latest stable, matching the local homebrew build).
+      - uses: gradle/actions/setup-gradle@v4
+        with:
+          gradle-version: current
       - name: Gradle test
         working-directory: clients/java
         run: gradle test