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/ui/keys.go

@@ -0,0 +1,77 @@
+package ui
+
+import "github.com/eslider/go-onlyoffice/cmd/office/model"
+
+// Action is a keyboard command outcome for the TUI.
+type Action int
+
+const (
+	ActionNone Action = iota
+	ActionMoveUp
+	ActionMoveDown
+	ActionToggleSelect
+	ActionOpenPreview
+	ActionNextPane
+	ActionRefresh
+	ActionQuit
+	ActionOpenVex
+)
+
+// KeyAction maps a key string and focused pane to an action.
+func KeyAction(key string, pane model.FocusPane) Action {
+	switch key {
+	case "q", "ctrl+c":
+		return ActionQuit
+	case "tab":
+		return ActionNextPane
+	case "r":
+		return ActionRefresh
+	case "up", "k":
+		return ActionMoveUp
+	case "down", "j":
+		return ActionMoveDown
+	case " ":
+		if pane == model.FocusList {
+			return ActionToggleSelect
+		}
+	case "enter":
+		if pane == model.FocusList {
+			return ActionOpenPreview
+		}
+	case "v":
+		if pane == model.FocusList {
+			return ActionOpenVex
+		}
+	}
+	return ActionNone
+}
+
+// LayoutWidths splits total terminal width into menu, list, preview columns.
+func LayoutWidths(total int) (menu, list, preview int) {
+	if total < 80 {
+		total = 80
+	}
+	menu = total / 5
+	if menu < 22 {
+		menu = 22
+	}
+	preview = total / 3
+	if preview < 28 {
+		preview = 28
+	}
+	list = total - menu - preview - 2
+	if list < 24 {
+		list = 24
+	}
+	return menu, list, preview
+}
+
+// ResolveMoveUp returns the action for upward navigation keys.
+func ResolveMoveUp(pane model.FocusPane) Action {
+	switch pane {
+	case model.FocusMenu, model.FocusList, model.FocusPreview:
+		return ActionMoveUp
+	default:
+		return ActionNone
+	}
+}