php: add ext-memcache extension to Docker image

The image installed php8.5-memcached but not php8.5-memcache, causing
composer to fail on projects requiring the ext-memcache extension.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Y4z1Mg9frZBGi8pK66BPwV

Author: claude

php/Dockerfile

@@ -31,7 +31,7 @@ RUN \
         php8.5-zip php8.5-bcmath php8.5-apcu php8.5-imagick \
         php8.5-xdebug php8.5-pcov \
         php8.5-igbinary php8.5-gmp php8.5-ldap \
-        php8.5-amqp php8.5-memcached php8.5-xsl php8.5-yaml \
+        php8.5-amqp php8.5-memcache php8.5-memcached php8.5-xsl php8.5-yaml \
         # GitHub CLI
         gh \
         # Chrome libs (agent-browser)