feat: order/delay in service files, enable cmd, --all on unit commands

- install/uninstall/start/stop/enable take <name> or --all; *all kept as shortcuts
- add enable (enable at boot + start); startall no longer enables
- order/delay resolved by config.ResolveOrder and written into systemd,
  OpenRC and runit service files (After=/sleep), so they apply at boot
- install --all stops and disables units before removing their files
- update regenerates all installed, enabled units and removes disabled ones
- edit creates the config dir; docs and man page updated
- tests: fake Init for cmd, ResolveOrder, backend ordering output

config/config.go

@@ -4,6 +4,8 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"sort"
+	"time"
 
 	"gopkg.in/yaml.v3"
 )
@@ -43,6 +45,10 @@ type Unit struct {
 	RestartSec     int    `yaml:"restart_sec,omitempty"`     // seconds between restarts
 	RestartRetries int    `yaml:"restart_retries,omitempty"` // max restart attempts (StartLimitBurst)
 
+	// Resolved from order/delay by Config.ResolveOrder; never stored.
+	After      []string      `yaml:"-"` // enabled same-user units of the previous order group
+	StartDelay time.Duration `yaml:"-"` // wait before start (zero for the first group)
+
 	// Stack fields (kind: stack) — one unit for a whole podman-compose project.
 	Kind         string   `yaml:"kind,omitempty"`          // container (default) | stack
 	Project      string   `yaml:"project,omitempty"`       // compose project name
@@ -102,9 +108,60 @@ func Load(path string) (*Config, error) {
 	if err := yaml.Unmarshal(data, &cfg); err != nil {
 		return nil, fmt.Errorf("parsing config: %w", err)
 	}
+	if err := cfg.ResolveOrder(); err != nil {
+		return nil, err
+	}
 	return &cfg, nil
 }
 
+// ResolveOrder fills After and StartDelay on every unit from order and delay.
+// After lists the enabled units of the nearest lower order group in the same
+// scope (user). StartDelay is the unit's own delay, ignored for the first
+// group. Call again after changing order, delay or enabled.
+func (c *Config) ResolveOrder() error {
+	delays := make([]time.Duration, len(c.Units))
+	for i := range c.Units {
+		if c.Units[i].Delay == "" {
+			continue
+		}
+		d, err := time.ParseDuration(c.Units[i].Delay)
+		if err != nil || d < 0 {
+			return fmt.Errorf("unit %q: invalid delay %q", c.Units[i].Name, c.Units[i].Delay)
+		}
+		delays[i] = d
+	}
+
+	for i := range c.Units {
+		u := &c.Units[i]
+		u.After, u.StartDelay = nil, 0
+		if !u.Enabled {
+			continue
+		}
+		hasLower, best := false, 0
+		for j := range c.Units {
+			o := c.Units[j]
+			if !o.Enabled || o.Order >= u.Order {
+				continue
+			}
+			hasLower = true
+			if o.User != u.User {
+				continue
+			}
+			switch {
+			case u.After == nil || o.Order > best:
+				best, u.After = o.Order, []string{o.Name}
+			case o.Order == best:
+				u.After = append(u.After, o.Name)
+			}
+		}
+		sort.Strings(u.After)
+		if hasLower {
+			u.StartDelay = delays[i]
+		}
+	}
+	return nil
+}
+
 // LoadOrEmpty loads the config file, or returns an empty config if it doesn't exist.
 func LoadOrEmpty(path string) (*Config, error) {
 	_, err := os.Stat(path)