feat(wireguard): selektiver .conf-Import — Auswahl einzelner Interfaces per Modal

- GET /wireguard/importable listet alle .conf-Dateien in /etc/wireguard/
  mit already_in-Flag (bereits in DB)
- POST /wireguard/import nimmt optionale Names-Liste; ohne Namen → alles
- edgeguard-ctl wg-import [iface…] importiert nur die genannten Interfaces
- UI: Checkbox-Modal mit "Alle neuen auswählen" + Einzelauswahl;
  bereits importierte Interfaces disabled + grüner Tag

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

internal/services/wireguard/import.go

@@ -47,6 +47,68 @@ func NewImporter(ifaces *InterfacesRepo, peers *PeersRepo, box *secrets.Box) *Im
 	return &Importer{Ifaces: ifaces, Peers: peers, Box: box}
 }
 
+// ImportableEntry describes one .conf file that can be imported.
+type ImportableEntry struct {
+	Name      string `json:"name"`       // interface name without .conf
+	AlreadyIn bool   `json:"already_in"` // already present in the DB
+}
+
+// ListImportable scans dir for *.conf files and reports which are new
+// (not yet in the DB) and which are already imported.
+func (im *Importer) ListImportable(ctx context.Context, dir string) ([]ImportableEntry, error) {
+	entries, err := os.ReadDir(dir)
+	if err != nil {
+		if errors.Is(err, fs.ErrNotExist) {
+			return nil, nil
+		}
+		return nil, err
+	}
+	existing, err := im.Ifaces.List(ctx)
+	if err != nil {
+		return nil, err
+	}
+	inDB := make(map[string]bool, len(existing))
+	for _, x := range existing {
+		inDB[x.Name] = true
+	}
+	var out []ImportableEntry
+	for _, e := range entries {
+		if e.IsDir() || !strings.HasSuffix(e.Name(), ".conf") {
+			continue
+		}
+		name := strings.TrimSuffix(e.Name(), ".conf")
+		if !validIfaceName(name) {
+			continue
+		}
+		out = append(out, ImportableEntry{Name: name, AlreadyIn: inDB[name]})
+	}
+	return out, nil
+}
+
+// ImportSelected imports only the named interfaces from dir.
+// An empty names slice is treated as "import all" (same as ImportDir).
+func (im *Importer) ImportSelected(ctx context.Context, dir string, names []string) (*ImportResult, error) {
+	if len(names) == 0 {
+		return im.ImportDir(ctx, dir)
+	}
+	res := &ImportResult{}
+	want := make(map[string]bool, len(names))
+	for _, n := range names {
+		want[n] = true
+	}
+	for name := range want {
+		if !validIfaceName(name) {
+			res.Skipped = append(res.Skipped, name+" (invalid name)")
+			continue
+		}
+		path := filepath.Join(dir, name+".conf")
+		if err := im.importFile(ctx, name, path, res); err != nil {
+			res.Skipped = append(res.Skipped, name+": "+err.Error())
+		}
+	}
+	return res, nil
+}
+
 func (im *Importer) ImportDir(ctx context.Context, dir string) (*ImportResult, error) {
 	res := &ImportResult{}
 	entries, err := os.ReadDir(dir)