feat(office): table detail panes and Alt+1/2/3 layout toggles

Add spreadsheet-style list, split detail pane with forms and document preview,
and Alt+1/2/3 to show/hide panes with even width distribution.

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

cmd/office/ui/scroll.go

@@ -0,0 +1,67 @@
+package ui
+
+import (
+	"github.com/charmbracelet/bubbles/viewport"
+	"github.com/eslider/go-onlyoffice/cmd/office/model"
+)
+
+func (m *Model) scrollFocusedPane(key string) bool {
+	switch m.focus {
+	case model.FocusMenu:
+		return scrollViewport(&m.menuVP, key)
+	case model.FocusList:
+		switch key {
+		case "pgdown", "pgdn", "f", "ctrl+d":
+			m.listTable.PageScroll(1)
+			return true
+		case "pgup", "b", "ctrl+u":
+			m.listTable.PageScroll(-1)
+			return true
+		}
+		return false
+	case model.FocusPreview:
+		if m.detail.Zone() != detailZoneContent || m.detail.mode != detailDocument {
+			return false
+		}
+		return scrollViewport(&m.detail.docVP, key)
+	default:
+		return false
+	}
+}
+
+func (m *Model) paneHeight() int {
+	h := m.height - 3
+	if h < 3 {
+		h = 3
+	}
+	return h
+}
+
+func (m *Model) paneInnerWidth(outer int) int {
+	if outer <= 0 {
+		return 8
+	}
+	w := outer - 2 // border only; content fills inner box
+	if w < 8 {
+		w = 8
+	}
+	return w
+}
+
+func scrollViewport(vp *viewport.Model, key string) bool {
+	switch key {
+	case "pgdown", "pgdn", "f", "ctrl+d":
+		vp.ViewDown()
+		return true
+	case "pgup", "b", "ctrl+u":
+		vp.ViewUp()
+		return true
+	case "home", "g":
+		vp.GotoTop()
+		return true
+	case "end", "G":
+		vp.GotoBottom()
+		return true
+	}
+	return false
+}