feat(files): project/task Documents API + oo projects|tasks files

Library (files.go):
- Types: FileEntry, FolderEntry, ProjectFilesResponse.
- GetProjectFiles, GetTaskFiles, GetFile, UploadProjectFile (POST .../upload),
  AttachFilesToTask (POST form files=), UploadTaskFile (upload+attach),
  DetachTaskFile (DELETE ?fileid=), RenameFile, DeleteFiles, DownloadFile.
- Helpers: FileEntryNumericID, FileEntryTitle, SafeLocalFileName, projectIDFromTaskMap.

http.go: putJSON for JSON PUT bodies.

CLI: oo projects files {list,upload,download,rename,delete}, oo tasks files
{list,upload,detach}; projects_files.go + tasks_files.go.

Tests: files_integration_test.go (live), files_test.go + testdata (decode).

Docs: CHANGELOG 0.6.0, README, AGENTS.md, cmd/oo/main.go tree.
Made-with: Cursor

files_test.go

@@ -0,0 +1,70 @@
+package onlyoffice
+
+import (
+	"encoding/json"
+	"os"
+	"testing"
+)
+
+func TestDecodeProjectFilesEnvelope(t *testing.T) {
+	raw, err := os.ReadFile("testdata/project_files_response.json")
+	if err != nil {
+		t.Fatal(err)
+	}
+	resp, err := responseField(json.RawMessage(raw), "response")
+	if err != nil {
+		t.Fatal(err)
+	}
+	var pf ProjectFilesResponse
+	if err := json.Unmarshal(resp, &pf); err != nil {
+		t.Fatal(err)
+	}
+	if len(pf.Folders) != 1 || pf.Folders[0].Title == nil || *pf.Folders[0].Title != "Subfolder" {
+		t.Fatalf("folders: %+v", pf.Folders)
+	}
+	if len(pf.Files) != 1 || pf.Files[0].Title == nil || *pf.Files[0].Title != "readme.txt" {
+		t.Fatalf("files: %+v", pf.Files)
+	}
+	if pf.Files[0].ID == nil || pf.Files[0].ID.String() != "100" {
+		t.Fatalf("file id: %v", pf.Files[0].ID)
+	}
+}
+
+func TestDecodeTaskFilesEnvelope(t *testing.T) {
+	raw, err := os.ReadFile("testdata/task_files_response.json")
+	if err != nil {
+		t.Fatal(err)
+	}
+	resp, err := responseField(json.RawMessage(raw), "response")
+	if err != nil {
+		t.Fatal(err)
+	}
+	var list []*FileEntry
+	if err := json.Unmarshal(resp, &list); err != nil {
+		t.Fatal(err)
+	}
+	if len(list) != 1 || list[0].Title == nil || *list[0].Title != "attach.pdf" {
+		t.Fatalf("list: %+v", list)
+	}
+}
+
+func TestProjectIDFromTaskMap(t *testing.T) {
+	m := map[string]any{
+		"projectOwner": map[string]any{"id": float64(33)},
+	}
+	if got := projectIDFromTaskMap(m); got != "33" {
+		t.Fatalf("got %q", got)
+	}
+	if projectIDFromTaskMap(nil) != "" {
+		t.Fatal("expected empty")
+	}
+}
+
+func TestSafeLocalFileName(t *testing.T) {
+	if got := SafeLocalFileName("  foo/bar.txt  "); got != "bar.txt" {
+		t.Fatalf("got %q", got)
+	}
+	if got := SafeLocalFileName(""); got != "download" {
+		t.Fatalf("got %q", got)
+	}
+}