Route cron output to container stdout/stderr

[StefanMarkmann]

Motivation

• Make scheduled backup logs surface in the container logs by routing cron job output to the container PID1 fds.
• Ensure the original timestamps emitted by /backup.sh remain intact by appending raw stdout/stderr to the container's main fds.
• Keep scheduled behavior unchanged while improving observability for scheduled runs.

Description

• Updated the cron entry in src/run.sh to append output redirection: ${SCHEDULE} /bin/sh /cron.sh >> /proc/1/fd/1 2>> /proc/1/fd/2.
• Retained the existing cron.sh wrapper which execs /bin/sh /backup.sh so backup output is forwarded untouched.
• File permissions and the scheduler invocation (crond -n -s) remain unchanged.

Testing

• No automated tests were executed in this environment.

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Codex Task