fix: gw relay systemd restart

[x032205]

Fixes issue with gateway & relay restarts when running with systemd.
Also fixes issue where --domain flag isn't read for auto relay selection in systemd command

[greptile-apps]

Greptile Summary

• Fixed systemd Type=notify services not properly signaling ready state, which prevented successful restarts of gateway and relay services
• Fixed --domain flag being ignored during automatic relay selection in systemd install command

Confidence Score: 5/5

• This PR is safe to merge with minimal risk
• The changes are straightforward bug fixes that add missing systemd notifications and fix flag handling. The systemd.SdNotify calls are placed correctly after service initialization and follow the same pattern already used in v1 gateway/relay. The domain flag fix ensures config.INFISICAL_URL is set before it's used in API calls, matching the behavior of other commands.
• No files require special attention

[greptile-apps]

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