fix(docker): install DateTime::TimeZone 2.71 for BC permanent UTC-7

Dockerfile

@@ -190,6 +190,13 @@ RUN cpanm install -n \
 	Net::SAML2 \
 	&& rm -fr ./cpanm /root/.cpanm /tmp/*
 
+# DateTime::TimeZone - Ubuntu 24.04 ships 2.62 (Olson 2024a) and never updates it, and DateTime
+# uses its own compiled zone data rather than /usr/share/zoneinfo. 2.68+ has BC's move to permanent
+# UTC-7 (no fall back on 2026-11-01). The check fails the build if America/Vancouver would still
+# fall back to UTC-8 in December 2026.
+RUN cpanm install -n DateTime::TimeZone@2.71 && rm -fr ./cpanm /root/.cpanm /tmp/* \
+	&& perl -MDateTime -e 'exit(DateTime->from_epoch(epoch => 1796126400, time_zone => "America/Vancouver")->offset == -7 * 3600 ? 0 : 1)'
+
 # ==================================================================
 # Phase 5 - Install webwork2 and pg which were downloaded to /opt/base/ in phase 1
 # Option: Install the OPL in the image also (about 850 MB)

Dockerfile-prod

@@ -87,15 +87,15 @@
 	PG_ROOT=$APP_ROOT/pg \
 	PATH=$PATH:$APP_ROOT/webwork2/bin
 
 ENV WEBWORK_DB_HOST db
 ENV WEBWORK_DB_PORT 3306
 ENV WEBWORK_DB_NAME webwork
 ENV WEBWORK_DB_USER webworkWrite
 ENV WEBWORK_DB_PASSWORD passwordRW
 ENV WEBWORK_SMTP_SERVER localhost
 ENV WEBWORK_SMTP_SENDER webwork@example.com
 ENV R_HOST r
 ENV DEBUG 0
 
 # ==================================================================
 # Phase 3 - Install required packages
@@ -248,6 +248,13 @@
 	Net::SAML2 \
 	&& rm -fr ./cpanm /root/.cpanm /tmp/*
 
+# DateTime::TimeZone - Ubuntu 24.04 ships 2.62 (Olson 2024a) and never updates it, and DateTime
+# uses its own compiled zone data rather than /usr/share/zoneinfo. 2.68+ has BC's move to permanent
+# UTC-7 (no fall back on 2026-11-01). The check fails the build if America/Vancouver would still
+# fall back to UTC-8 in December 2026.
+RUN cpanm install -n DateTime::TimeZone@2.71 && rm -fr ./cpanm /root/.cpanm /tmp/* \
+	&& perl -MDateTime -e 'exit(DateTime->from_epoch(epoch => 1796126400, time_zone => "America/Vancouver")->offset == -7 * 3600 ? 0 : 1)'
+
 # App::Genpass - used by LTI1p3's CourseUpdater
 # Data::ObjectDriver - used by DelayedJob
 # Bytes::Random::Secure::Tiny - used by LTI1p3 for secure random string