feat(oo): file deep links, login check, replace-in (fresh upload)

- link: print Products/Files/DocEditor.aspx?fileid=… deep links (title+url)
- lib: FileEditorURL/FolderURL helpers (+tests)
- users check: verify credentials (userName vs email) via authentication.json
- projects files replace-in FOLDER_ID FILE...: hard delete same stem|ext in a
  folder + fresh upload → single clean version (no version history)

links_test.go

@@ -0,0 +1,24 @@
+package onlyoffice
+
+import "testing"
+
+func TestFileEditorURL(t *testing.T) {
+	cases := []struct{ base, id, want string }{
+		{"https://office.example.com", "3651", "https://office.example.com/Products/Files/DocEditor.aspx?fileid=3651"},
+		{"https://office.example.com/", " 3687 ", "https://office.example.com/Products/Files/DocEditor.aspx?fileid=3687"},
+		{"http://localhost:8087", "a/b", "http://localhost:8087/Products/Files/DocEditor.aspx?fileid=a%2Fb"},
+	}
+	for _, c := range cases {
+		if got := FileEditorURL(c.base, c.id); got != c.want {
+			t.Fatalf("FileEditorURL(%q,%q) = %q, want %q", c.base, c.id, got, c.want)
+		}
+	}
+}
+
+func TestFolderURL(t *testing.T) {
+	got := FolderURL("https://office.example.com/", "495")
+	want := "https://office.example.com/Products/Files/Default.aspx#folder=495"
+	if got != want {
+		t.Fatalf("FolderURL = %q, want %q", got, want)
+	}
+}