fix(ci): add ondrej/php PPA for PHP 8.2 on ubuntu-latest runners

The gitea/runner-images:ubuntu-latest image does not ship PHP 8.2
packages in default repos, causing Gate 1 and all downstream gates
to fail with exit code 100. Adding ppa:ondrej/php resolves this.

Authored-by: Moko Consulting
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.mokogitea/workflows/ci-platform.yml

@@ -82,6 +82,7 @@ jobs:
 
       - name: Setup PHP ${{ env.PHP_VERSION }}
         run: |
+          sudo add-apt-repository -y ppa:ondrej/php >/dev/null 2>&1
           sudo apt-get update -qq
           sudo apt-get install -y -qq php${{ env.PHP_VERSION }}-cli php${{ env.PHP_VERSION }}-mbstring \
             php${{ env.PHP_VERSION }}-xml php${{ env.PHP_VERSION }}-curl php${{ env.PHP_VERSION }}-zip \
@@ -164,6 +165,7 @@ jobs:
 
       - name: Setup PHP ${{ matrix.php }}
         run: |
+          sudo add-apt-repository -y ppa:ondrej/php >/dev/null 2>&1
           sudo apt-get update -qq
           sudo apt-get install -y -qq php${{ matrix.php }}-cli php${{ matrix.php }}-mbstring \
             php${{ matrix.php }}-xml php${{ matrix.php }}-curl php${{ matrix.php }}-zip \
@@ -198,6 +200,7 @@ jobs:
 
       - name: Setup PHP
         run: |
+          sudo add-apt-repository -y ppa:ondrej/php >/dev/null 2>&1
           sudo apt-get update -qq
           sudo apt-get install -y -qq php${{ env.PHP_VERSION }}-cli php${{ env.PHP_VERSION }}-mbstring \
             php${{ env.PHP_VERSION }}-xml php${{ env.PHP_VERSION }}-curl php${{ env.PHP_VERSION }}-zip >/dev/null 2>&1
@@ -245,6 +248,7 @@ jobs:
 
       - name: Setup PHP
         run: |
+          sudo add-apt-repository -y ppa:ondrej/php >/dev/null 2>&1
           sudo apt-get update -qq
           sudo apt-get install -y -qq php${{ env.PHP_VERSION }}-cli php${{ env.PHP_VERSION }}-mbstring \
             php${{ env.PHP_VERSION }}-xml php${{ env.PHP_VERSION }}-curl >/dev/null 2>&1