Extract Files seam, WebDAV, and Visit from CheckDNS.

Publish go-nc-files v1 with local/WebDAV Root, DefaultPathStore, and
neutral Working Folder language; depends on go-nc-exapp v0.1.0.

Co-authored-by: Cursor <cursoragent@cursor.com>

defaultpath.go

@@ -0,0 +1,65 @@
+package goncfiles
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// DefaultPathStore persists the Saved Default Working Folder path (User Files Root–relative).
+type DefaultPathStore interface {
+	GetDefault() (string, error)
+	SetDefault(rel string) error
+}
+
+// FileStore is the local-adapter settings JSON file.
+type FileStore struct {
+	Path string
+}
+
+type settingsFile struct {
+	DefaultPath string `json:"defaultPath"`
+}
+
+// GetDefault reads the saved default; empty means the caller should use the product initial default.
+func (s FileStore) GetDefault() (string, error) {
+	body, err := os.ReadFile(s.Path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return "", nil
+		}
+		return "", err
+	}
+	var sf settingsFile
+	if err := json.Unmarshal(body, &sf); err != nil {
+		return "", err
+	}
+	return strings.TrimSpace(sf.DefaultPath), nil
+}
+
+// SetDefault writes the saved Working Folder path.
+func (s FileStore) SetDefault(rel string) error {
+	body, err := json.MarshalIndent(settingsFile{DefaultPath: rel}, "", "  ")
+	if err != nil {
+		return err
+	}
+	if err := os.MkdirAll(filepath.Dir(s.Path), 0o755); err != nil {
+		return err
+	}
+	return os.WriteFile(s.Path, append(body, '\n'), 0o644)
+}
+
+// Memory is an in-memory DefaultPathStore for tests.
+type Memory struct {
+	Value string
+}
+
+// GetDefault returns the in-memory value.
+func (m *Memory) GetDefault() (string, error) { return m.Value, nil }
+
+// SetDefault stores the value in memory.
+func (m *Memory) SetDefault(rel string) error {
+	m.Value = rel
+	return nil
+}