`DefaultLimitNOFILESoft` is not a valid systemd configuration key.
systemd silently ignores it and emits this warning on every boot,
for both the system manager (PID 1) and the user manager:
Unknown key 'DefaultLimitNOFILESoft' in section [Manager], ignoring.
The consequence is that the script's stated goal of raising the soft
fd limit from 1024 to 65536 has not actually been happening: dev
tools (VS Code, Docker, dev servers, databases) continue to run with
systemd's default 1024 soft limit.
The valid key is `DefaultLimitNOFILE`, which accepts either a single
value (sets both soft and hard) or `SOFT:HARD`. Using `65536:524288`
raises the soft limit while preserving systemd's typical 524288
hard-limit default — using the bare `=65536` form would lower the
hard limit, which would be a regression.
After this change and `systemctl daemon-reexec` on both managers,
`systemctl show | grep DefaultLimitNOFILE` reports:
DefaultLimitNOFILE=524288 (hard)
DefaultLimitNOFILESoft=65536 (soft, derived display attribute)
and the boot-time "Unknown key" warnings disappear.
(The typo likely originated from someone reading `systemctl show`
output, where `DefaultLimitNOFILESoft=` appears as a read-only
display attribute for the soft component of the parsed limit.
It looks like a config key but isn't.)
