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

cmd/order.go

@@ -0,0 +1,67 @@
+package cmd
+
+import (
+	"fmt"
+	"io"
+	"sort"
+	"sync"
+
+	"github.com/warkanum/unitdore/config"
+)
+
+// sortUnits returns a copy of units sorted by order then name; reverse flips both.
+func sortUnits(units []config.Unit, reverse bool) []config.Unit {
+	out := make([]config.Unit, len(units))
+	copy(out, units)
+	sort.SliceStable(out, func(i, j int) bool {
+		if out[i].Order != out[j].Order {
+			return (out[i].Order < out[j].Order) != reverse
+		}
+		return (out[i].Name < out[j].Name) != reverse
+	})
+	return out
+}
+
+// groupByOrder splits order-sorted units into groups sharing the same order.
+func groupByOrder(sorted []config.Unit) [][]config.Unit {
+	var groups [][]config.Unit
+	for _, u := range sorted {
+		n := len(groups)
+		if n > 0 && groups[n-1][0].Order == u.Order {
+			groups[n-1] = append(groups[n-1], u)
+			continue
+		}
+		groups = append(groups, []config.Unit{u})
+	}
+	return groups
+}
+
+// runOrdered runs fn for every unit: groups of equal order one after another,
+// units within a group in parallel. Start delays live in the generated service
+// files, so a blocking start covers them. Output is printed per group in name
+// order. Returns the number of units fn succeeded and failed for.
+func runOrdered(units []config.Unit, w io.Writer, fn func(u config.Unit) (string, error)) (ok, failed int) {
+	for _, g := range groupByOrder(sortUnits(units, false)) {
+		msgs := make([]string, len(g))
+		errs := make([]error, len(g))
+		var wg sync.WaitGroup
+		for j, u := range g {
+			wg.Add(1)
+			go func(j int, u config.Unit) {
+				defer wg.Done()
+				msgs[j], errs[j] = fn(u)
+			}(j, u)
+		}
+		wg.Wait()
+		for j, u := range g {
+			if errs[j] != nil {
+				fmt.Fprintf(w, "  ✗ failed: %s: %v\n", u.Name, errs[j])
+				failed++
+				continue
+			}
+			fmt.Fprintf(w, "  ✓ %s\n", msgs[j])
+			ok++
+		}
+	}
+	return ok, failed
+}