feat: add systemd user services and timer units

- Create systemd user service files for both Go and Rust implementations
- Add comprehensive timer configurations: 30-minute, hourly, and daily schedules
- Include security settings, resource limits, and proper service dependencies
- Add justfile recipes for service management (install, enable, disable, status)
- Remove deprecated Makefile in favor of just-based build system
- Fix Rust compilation warnings in imap.rs

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

systemd/mail2couch-go-daily.timer

@@ -0,0 +1,17 @@
+[Unit]
+Description=Run mail2couch Go Implementation daily
+Documentation=https://kode.naiv.no/olemd/mail2couch
+Requires=mail2couch-go.service
+
+[Timer]
+# Run daily at 2:30 AM with some randomization
+OnCalendar=*-*-* 02:30:00
+# Run 10 minutes after boot if we missed a scheduled run
+OnBootSec=10min
+# If the system was off, run shortly after startup
+Persistent=true
+# Add up to 30 minutes randomization to spread load
+RandomizedDelaySec=1800
+
+[Install]
+WantedBy=timers.target

systemd/mail2couch-go-hourly.timer

@@ -0,0 +1,17 @@
+[Unit]
+Description=Run mail2couch Go Implementation every hour
+Documentation=https://kode.naiv.no/olemd/mail2couch
+Requires=mail2couch-go.service
+
+[Timer]
+# Run every hour at a random minute to spread load
+OnCalendar=hourly
+# Run 5 minutes after boot if we missed a scheduled run
+OnBootSec=5min
+# If the system was off, run shortly after startup
+Persistent=true
+# Add randomization to avoid all users hitting servers simultaneously
+RandomizedDelaySec=600
+
+[Install]
+WantedBy=timers.target

systemd/mail2couch-go.service

@@ -0,0 +1,35 @@
+[Unit]
+Description=mail2couch Go Implementation - Email backup to CouchDB
+Documentation=https://kode.naiv.no/olemd/mail2couch
+After=network.target
+Wants=network.target
+
+[Service]
+Type=oneshot
+User=%i
+ExecStart=%h/bin/mail2couch-go
+WorkingDirectory=%h/.config/mail2couch
+
+# Environment
+Environment=PATH=%h/bin:/usr/local/bin:/usr/bin:/bin
+
+# Logging
+StandardOutput=journal
+StandardError=journal
+SyslogIdentifier=mail2couch-go
+
+# Security settings
+NoNewPrivileges=yes
+PrivateTmp=yes
+ProtectSystem=strict
+ProtectHome=read-only
+ReadOnlyPaths=/
+ReadWritePaths=%h/.config/mail2couch %h/.local/share/mail2couch
+
+# Resource limits
+MemoryHigh=512M
+MemoryMax=1G
+CPUQuota=50%
+
+[Install]
+WantedBy=default.target

systemd/mail2couch-go.timer

@@ -0,0 +1,17 @@
+[Unit]
+Description=Run mail2couch Go Implementation every 30 minutes
+Documentation=https://kode.naiv.no/olemd/mail2couch
+Requires=mail2couch-go.service
+
+[Timer]
+# Run every 30 minutes
+OnCalendar=*:0/30
+# Run 2 minutes after boot if we missed a scheduled run
+OnBootSec=2min
+# If the system was off, run shortly after startup
+Persistent=true
+# Add some randomization to avoid all users hitting servers simultaneously
+RandomizedDelaySec=300
+
+[Install]
+WantedBy=timers.target

systemd/mail2couch-rs-daily.timer

@@ -0,0 +1,17 @@
+[Unit]
+Description=Run mail2couch Rust Implementation daily
+Documentation=https://kode.naiv.no/olemd/mail2couch
+Requires=mail2couch-rs.service
+
+[Timer]
+# Run daily at 2:30 AM with some randomization
+OnCalendar=*-*-* 02:30:00
+# Run 10 minutes after boot if we missed a scheduled run
+OnBootSec=10min
+# If the system was off, run shortly after startup
+Persistent=true
+# Add up to 30 minutes randomization to spread load
+RandomizedDelaySec=1800
+
+[Install]
+WantedBy=timers.target

systemd/mail2couch-rs-hourly.timer

@@ -0,0 +1,17 @@
+[Unit]
+Description=Run mail2couch Rust Implementation every hour
+Documentation=https://kode.naiv.no/olemd/mail2couch
+Requires=mail2couch-rs.service
+
+[Timer]
+# Run every hour at a random minute to spread load
+OnCalendar=hourly
+# Run 5 minutes after boot if we missed a scheduled run
+OnBootSec=5min
+# If the system was off, run shortly after startup
+Persistent=true
+# Add randomization to avoid all users hitting servers simultaneously
+RandomizedDelaySec=600
+
+[Install]
+WantedBy=timers.target

systemd/mail2couch-rs.service

@@ -0,0 +1,36 @@
+[Unit]
+Description=mail2couch Rust Implementation - Email backup to CouchDB
+Documentation=https://kode.naiv.no/olemd/mail2couch
+After=network.target
+Wants=network.target
+
+[Service]
+Type=oneshot
+User=%i
+ExecStart=%h/bin/mail2couch-rs
+WorkingDirectory=%h/.config/mail2couch
+
+# Environment
+Environment=PATH=%h/bin:/usr/local/bin:/usr/bin:/bin
+Environment=RUST_LOG=info
+
+# Logging
+StandardOutput=journal
+StandardError=journal
+SyslogIdentifier=mail2couch-rs
+
+# Security settings
+NoNewPrivileges=yes
+PrivateTmp=yes
+ProtectSystem=strict
+ProtectHome=read-only
+ReadOnlyPaths=/
+ReadWritePaths=%h/.config/mail2couch %h/.local/share/mail2couch
+
+# Resource limits
+MemoryHigh=512M
+MemoryMax=1G
+CPUQuota=50%
+
+[Install]
+WantedBy=default.target

systemd/mail2couch-rs.timer

@@ -0,0 +1,17 @@
+[Unit]
+Description=Run mail2couch Rust Implementation every 30 minutes
+Documentation=https://kode.naiv.no/olemd/mail2couch
+Requires=mail2couch-rs.service
+
+[Timer]
+# Run every 30 minutes
+OnCalendar=*:0/30
+# Run 2 minutes after boot if we missed a scheduled run
+OnBootSec=2min
+# If the system was off, run shortly after startup
+Persistent=true
+# Add some randomization to avoid all users hitting servers simultaneously
+RandomizedDelaySec=300
+
+[Install]
+WantedBy=timers.target