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/preview/render.go

@@ -0,0 +1,23 @@
+package preview
+
+import (
+	"github.com/charmbracelet/glamour"
+)
+
+// RenderMarkdown renders GitHub-flavoured markdown for terminal display.
+func RenderMarkdown(md string, width int) (string, error) {
+	if md == "" {
+		return "", nil
+	}
+	if width < 20 {
+		width = 20
+	}
+	r, err := glamour.NewTermRenderer(
+		glamour.WithAutoStyle(),
+		glamour.WithWordWrap(width),
+	)
+	if err != nil {
+		return "", err
+	}
+	return r.Render(md)
+}