Move install-time system configuration to update pipeline

[MagnaCapax]

Problem

install.sh currently performs system configuration that should be in the update pipeline. These configurations are important for all servers, but only run on fresh installs. Servers installed before these were added to install.sh will never receive them via update.php.

Items currently in install.sh that should move to update pipeline

1. /proc hidepid=2 setup in fstab
2. GRUB systemd.unified_cgroup_hierarchy=0 addition
3. sysctl BFQ scheduler + read_ahead_kb tuning (via install_sysctl_defaults)
4. chmod o-rw /home
5. Post-install scripts: setupRootCron.php, setupSkelPermissions.php, quotaFix.php, ftpConfig.php

Proposed Solution

Move these configurations to update-step2.php (or equivalent update pipeline step) so they apply on every update, not just fresh installs. This ensures all servers in the fleet converge to the same configuration state over time.

Notes

• Low priority code maintenance — not urgent
• Difficult to test because it changes the install/update flow
• install.sh should be just a bootstrapper that hands off to update.php