feat(network): VLAN/bridge/bond interface provisioner + IP-address apply

Fügt zwei neue systemd-oneshot-Services hinzu:
- edgeguard-interfaces.service: erstellt VLAN/bridge/bond-Interfaces
  (ip link add/del) wenn der Operator sie über die GUI anlegt/entfernt.
  Ethernet + WireGuard bleiben OS-managed.
- edgeguard-ipaddresses.service: bindet/entfernt IP-Adressen (ip addr
  add/del) nach jeder GUI-Mutation; läuft jetzt After=edgeguard-interfaces
  damit Interfaces immer vor den Adressen existieren.

Beide Services triggern per applyAsync() in den zugehörigen Handlern
(networks.go → Interfaces, ipaddresses.go → Adressen). Diff-Ansatz
über *-applied.conf verhindert dass manuell gebundene Adressen/
Interfaces angefasst werden.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/services/ipaddresses/apply.go

@@ -0,0 +1,87 @@
+package ipaddresses
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"os/exec"
+	"strings"
+
+	"git.netcell-it.de/projekte/edgeguard-native/internal/configgen"
+)
+
+// ConfPath wird von edgeguard-apply-ipaddresses gelesen.
+const ConfPath = "/etc/edgeguard/ip-addresses.conf"
+
+type Generator struct {
+	Repo *Repo
+}
+
+func NewGenerator(repo *Repo) *Generator { return &Generator{Repo: repo} }
+
+// Render schreibt /etc/edgeguard/ip-addresses.conf (Format: dev|addr/prefix)
+// und triggert das apply-Skript via sudo.
+func (g *Generator) Render(ctx context.Context) error {
+	type addrRow struct {
+		dev    string
+		addr   string
+		prefix int
+	}
+
+	rows, err := g.Repo.Pool.Query(ctx, `
+		SELECT ni.name, ia.address, ia.prefix
+		FROM ip_addresses ia
+		JOIN network_interfaces ni ON ni.id = ia.interface_id
+		WHERE ia.active = true
+		ORDER BY ni.name, ia.address`,
+	)
+	if err != nil {
+		return fmt.Errorf("query: %w", err)
+	}
+	defer rows.Close()
+
+	var entries []addrRow
+	for rows.Next() {
+		var r addrRow
+		if err := rows.Scan(&r.dev, &r.addr, &r.prefix); err != nil {
+			return fmt.Errorf("scan: %w", err)
+		}
+		entries = append(entries, r)
+	}
+	if err := rows.Err(); err != nil {
+		return err
+	}
+
+	var buf bytes.Buffer
+	buf.WriteString("# Generated by edgeguard-api — DO NOT EDIT.\n")
+	buf.WriteString("# Read by edgeguard-apply-ipaddresses. Format: dev|address/prefix\n")
+	for _, e := range entries {
+		fmt.Fprintf(&buf, "%s|%s/%d\n",
+			sanitize(e.dev), sanitize(e.addr), e.prefix)
+	}
+
+	if err := configgen.AtomicWrite(ConfPath, buf.Bytes(), 0o644); err != nil {
+		return fmt.Errorf("write %s: %w", ConfPath, err)
+	}
+	if err := applyIPAddresses(); err != nil {
+		return fmt.Errorf("apply: %w", err)
+	}
+	return nil
+}
+
+func applyIPAddresses() error {
+	cmd := exec.Command("sudo", "-n", "/usr/bin/systemctl",
+		"restart", "edgeguard-ipaddresses.service")
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		return fmt.Errorf("systemctl restart edgeguard-ipaddresses.service: %s: %w",
+			strings.TrimSpace(string(out)), err)
+	}
+	return nil
+}
+
+func sanitize(s string) string {
+	s = strings.ReplaceAll(s, "|", "")
+	s = strings.ReplaceAll(s, "\n", "")
+	return strings.TrimSpace(s)
+}