chore: move business tooling out of the public library; tidy filestore naming

Keep the public tree project-generic. Business/one-off tools, deployment
and business docs move to the private oo-workspace repo.

Moved to oo-workspace:
- cmd/ooscan, cmd/pdfamount, cmd/kontoblatt, cmd/kontolink
- internal/xlspipe (cutover-portugal workbook) -> oow workbook build
  (drops the --template/--title flags from oo docs put-xlsx)
- deploy/docker-compose.rclone-webdav.yml + docs/rclone-webdav.md
- docs/crm-associations.md

Removed GitHub-era leftovers:
- .github/workflows/release-please.yml, release-please-config.json,
  .release-please-manifest.json (tags are created on Gitea per SemVer)

Naming: the FileStore subsystem is now filestore_*.go (was file_*.go) to
match files_*.go (project Documents). Docs/AGENTS/README updated.

filestore_rest.go

@@ -0,0 +1,256 @@
+package onlyoffice
+
+// restStore implements FileStore on top of the REST Documents methods in
+// files.go. It is a thin adapter: no endpoint logic lives here, and every call
+// is wrapped in DoRetry.
+
+import (
+	"context"
+	"encoding/json"
+	"io"
+	"os"
+	"path/filepath"
+)
+
+// restStore is a FileStore over the REST Documents API.
+type restStore struct{ c *Client }
+
+// Name reports the backend name.
+func (s *restStore) Name() string { return ProviderREST }
+
+// List returns the files and folders directly below parentID.
+func (s *restStore) List(ctx context.Context, parentID string) ([]Entry, error) {
+	var out []Entry
+	err := retryStoreOp(ctx, func() error {
+		raw, err := s.c.ListFolder(ctx, parentID)
+		if err != nil {
+			return err
+		}
+		entries, err := entriesFromFolderMap(raw, ProviderREST)
+		if err != nil {
+			return err
+		}
+		out = entries
+		return nil
+	})
+	return out, err
+}
+
+// Stat returns file or folder metadata. Folders are resolved through the
+// listing endpoint (their own id appears as the listing's Current); other ids
+// fall back to the file metadata API.
+func (s *restStore) Stat(ctx context.Context, id string) (Entry, error) {
+	return s.stat(ctx, id)
+}
+
+// stat resolves a single id to a folder or file Entry.
+func (s *restStore) stat(ctx context.Context, id string) (Entry, error) {
+	var out Entry
+	err := retryStoreOp(ctx, func() error {
+		if l, err := s.c.ListDavFolder(ctx, id); err == nil {
+			if l != nil && l.Current.ID != "" && l.Current.ID == id {
+				out = DavFolderToEntry(l.Current, ProviderREST)
+				return nil
+			}
+		} else if Transient(err) {
+			return err
+		}
+		f, err := s.c.GetFile(ctx, id)
+		if err != nil {
+			return err
+		}
+		out = FileEntryToEntry(f, ProviderREST)
+		return nil
+	})
+	return out, err
+}
+
+// CreateFolder creates a subfolder under parentID.
+func (s *restStore) CreateFolder(ctx context.Context, parentID, title string) (Entry, error) {
+	var out Entry
+	err := retryStoreOp(ctx, func() error {
+		m, err := s.c.CreateFolder(ctx, parentID, title)
+		if err != nil {
+			return err
+		}
+		e, err := folderEntryFromMap(m, parentID, ProviderREST)
+		if err != nil {
+			return err
+		}
+		if e.ParentID == "" {
+			e.ParentID = parentID
+		}
+		if e.Title == "" {
+			e.Title = title
+		}
+		out = e
+		return nil
+	})
+	return out, err
+}
+
+// Upload streams r into parentID as title. UploadToFolder is path based, so
+// the reader is spooled to a temporary file first (ponytail: OnlyOffice
+// multipart upload buffers the whole body anyway).
+func (s *restStore) Upload(ctx context.Context, parentID, title string, r io.Reader) (Entry, error) {
+	dir, err := os.MkdirTemp("", "oo-rest-upload-")
+	if err != nil {
+		return Entry{}, err
+	}
+	defer os.RemoveAll(dir)
+
+	local := filepath.Join(dir, SafeLocalFileName(title))
+	f, err := os.Create(local)
+	if err != nil {
+		return Entry{}, err
+	}
+	if _, err := io.Copy(f, r); err != nil {
+		f.Close()
+		return Entry{}, err
+	}
+	if err := f.Close(); err != nil {
+		return Entry{}, err
+	}
+
+	var out Entry
+	err = retryStoreOp(ctx, func() error {
+		fe, err := s.c.UploadToFolder(ctx, parentID, local)
+		if err != nil {
+			return err
+		}
+		out = FileEntryToEntry(fe, ProviderREST)
+		return nil
+	})
+	return out, err
+}
+
+// Download streams the file bytes into w.
+func (s *restStore) Download(ctx context.Context, id string, w io.Writer) (int64, error) {
+	var n int64
+	err := retryStoreOp(ctx, func() error {
+		var e error
+		n, e = s.c.DownloadFile(ctx, id, w)
+		return e
+	})
+	return n, err
+}
+
+// Move moves folders and/or files into parentID. Ids are classified through
+// stat so folder moves use folderIds and file moves use fileIds on the shared
+// fileops/move endpoint.
+func (s *restStore) Move(ctx context.Context, ids []string, parentID string) error {
+	folders, files, err := s.split(ctx, ids)
+	if err != nil {
+		return err
+	}
+	if len(folders) == 0 && len(files) == 0 {
+		return nil
+	}
+	return retryStoreOp(ctx, func() error {
+		return s.c.MoveDavItems(ctx, folders, files, parentID)
+	})
+}
+
+// Copy copies folders and/or files into parentID. files.go has no copy method,
+// so the shared REST fileops copy endpoint (CopyDavItems) is used.
+func (s *restStore) Copy(ctx context.Context, ids []string, parentID string) error {
+	folders, files, err := s.split(ctx, ids)
+	if err != nil {
+		return err
+	}
+	if len(folders) == 0 && len(files) == 0 {
+		return nil
+	}
+	return retryStoreOp(ctx, func() error {
+		return s.c.CopyDavItems(ctx, folders, files, parentID)
+	})
+}
+
+// Rename sets a new title (including extension) for a file or folder.
+func (s *restStore) Rename(ctx context.Context, id, title string) error {
+	e, err := s.stat(ctx, id)
+	if err != nil {
+		return err
+	}
+	if e.Kind == Folder {
+		return retryStoreOp(ctx, func() error {
+			return s.c.RenameDavFolder(ctx, id, title)
+		})
+	}
+	return retryStoreOp(ctx, func() error {
+		_, err := s.c.RenameFile(ctx, id, title)
+		return err
+	})
+}
+
+// Delete permanently deletes folders and/or files.
+func (s *restStore) Delete(ctx context.Context, ids []string) error {
+	folders, files, err := s.split(ctx, ids)
+	if err != nil {
+		return err
+	}
+	if len(folders) == 0 && len(files) == 0 {
+		return nil
+	}
+	return retryStoreOp(ctx, func() error {
+		return s.c.DeleteDavItems(ctx, folders, files)
+	})
+}
+
+// split classifies ids into folder and file id lists.
+func (s *restStore) split(ctx context.Context, ids []string) (folders, files []string, err error) {
+	for _, id := range ids {
+		e, err := s.stat(ctx, id)
+		if err != nil {
+			return nil, nil, err
+		}
+		if e.Kind == Folder {
+			folders = append(folders, id)
+		} else {
+			files = append(files, id)
+		}
+	}
+	return folders, files, nil
+}
+
+// entriesFromFolderMap converts a ListFolder response map into canonical
+// entries, reusing the DavFile/DavFolder decoders for robust size handling.
+func entriesFromFolderMap(m map[string]any, provider string) ([]Entry, error) {
+	if m == nil {
+		return nil, nil
+	}
+	b, err := json.Marshal(m)
+	if err != nil {
+		return nil, err
+	}
+	var listing DavListing
+	if err := json.Unmarshal(b, &listing); err != nil {
+		return nil, err
+	}
+	out := make([]Entry, 0, len(listing.Folders)+len(listing.Files))
+	for _, f := range listing.Folders {
+		out = append(out, DavFolderToEntry(f, provider))
+	}
+	for _, f := range listing.Files {
+		out = append(out, DavFileToEntry(f, provider))
+	}
+	return out, nil
+}
+
+// folderEntryFromMap converts a CreateFolder response map into a folder Entry.
+func folderEntryFromMap(m map[string]any, parentID, provider string) (Entry, error) {
+	e := Entry{Kind: Folder, Provider: provider, ParentID: parentID}
+	if m == nil {
+		return e, nil
+	}
+	b, err := json.Marshal(m)
+	if err != nil {
+		return e, err
+	}
+	var f DavFolder
+	if err := json.Unmarshal(b, &f); err != nil {
+		return e, err
+	}
+	e = DavFolderToEntry(f, provider)
+	return e, nil
+}