feat(office): add Workspace TUI with shared bootstrap and test suite

Introduce the office Bubble Tea browser (module tree, multi-select lists,
markdown preview) alongside oo, with cmd/internal/bootstrap for shared auth,
unit tests across preview/model/ui/fetch, CI build for both binaries, and
GoReleaser archives for office.

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

cmd/office/main.go

@@ -0,0 +1,34 @@
+// Command office is a terminal UI for OnlyOffice Workspace.
+//
+// Three-pane layout: module tree (left), selectable list (center),
+// markdown preview (right). Uses github.com/eslider/go-onlyoffice for API calls.
+//
+// Build & install:
+//
+//	go install github.com/eslider/go-onlyoffice/cmd/office@latest
+package main
+
+import (
+	"context"
+	"fmt"
+	"os"
+
+	tea "github.com/charmbracelet/bubbletea"
+	"github.com/eslider/go-onlyoffice/cmd/internal/bootstrap"
+	"github.com/eslider/go-onlyoffice/cmd/office/ui"
+)
+
+func main() {
+	client, err := bootstrap.NewClient(context.Background())
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+
+	m := ui.NewModel(client)
+	p := tea.NewProgram(m, tea.WithAltScreen())
+	if _, err := p.Run(); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}