Adds two systemd user services to automatically unlock the rbw vault:
- rbw-unlock-on-login: Runs at graphical session start
- rbw-unlock-on-resume: Runs after resuming from suspend
This solves the issue of mbsync prompting for password every 5 minutes.
Once unlocked, the vault stays unlocked as long as mbsync syncs every
5 minutes (which resets the 1-hour lock timeout). Only prompts at login
or after long suspend periods.