feat(office): mail preview, infinite scroll, pane resize, and scrollbars

Polish the office TUI with proportional pane layout, drag resize, live
filtering, HTML mail preview, paginated mail lists, overflow scrollbars,
flattened navigation, and project save/status fixes; add UpdateProjectStatus.

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

cmd/office/ui/table_test.go

@@ -5,6 +5,7 @@ import (
 	"testing"
 
 	"github.com/eslider/go-onlyoffice/cmd/office/model"
+	"github.com/mattn/go-runewidth"
 )
 
 func sampleItems() []model.Item {
@@ -32,7 +33,7 @@ func TestDataTableMoveColScrolls(t *testing.T) {
 	items[0] = model.Item{ID: "1", Title: "One", Raw: map[string]any{
 		"alpha": "a", "beta": "b", "gamma": "c", "delta": "d",
 	}}
-	tbl.SetData(model.ListSpec{Subject: model.SubjectTasks}, items)
+	tbl.SetData(model.ListSpec{Subject: model.SubjectContacts}, items)
 	last := len(tbl.columns) - 1
 	tbl.cursorCol = last
 	tbl.ensureColVisible()
@@ -88,6 +89,55 @@ func TestDistributeColumnWidthsFillsTotal(t *testing.T) {
 	}
 }
 
+func TestTruncateCellText(t *testing.T) {
+	long := strings.Repeat("x", 40)
+	got := truncateCellText(long, 10)
+	if runewidth.StringWidth(got) > 10 {
+		t.Fatalf("truncated width=%d want <=10", runewidth.StringWidth(got))
+	}
+	if !strings.HasSuffix(got, "...") {
+		t.Fatalf("expected ellipsis suffix, got %q", got)
+	}
+}
+
+func TestDataTableTruncatesNonSelectedRows(t *testing.T) {
+	long := strings.Repeat("A", 60)
+	items := []model.Item{
+		{ID: "1", Title: "Short"},
+		{ID: "2", Title: long},
+	}
+	tbl := newDataTable()
+	tbl.SetSize(50, 10)
+	tbl.SetData(model.ListSpec{Subject: model.SubjectTasks}, items)
+	tbl.cursorRow = 0
+
+	if strings.Contains(tbl.renderRow(1), long) {
+		t.Fatal("non-cursor row should truncate long title")
+	}
+
+	tbl.cursorRow = 1
+	if !strings.Contains(tbl.renderRow(1), long) {
+		t.Fatal("cursor row should show full title")
+	}
+}
+
+func TestDataTableShowsFullTextWhenSpaceSelected(t *testing.T) {
+	long := strings.Repeat("B", 60)
+	items := []model.Item{
+		{ID: "1", Title: "Short"},
+		{ID: "2", Title: long, Selected: true},
+	}
+	tbl := newDataTable()
+	tbl.SetSize(50, 10)
+	tbl.SetData(model.ListSpec{Subject: model.SubjectTasks}, items)
+	tbl.cursorRow = 0
+
+	rowSelected := tbl.renderRow(1)
+	if !strings.Contains(rowSelected, long) {
+		t.Fatal("space-selected row should show full title")
+	}
+}
+
 func indexOfColumn(tbl DataTable, key string) int {
 	for i, c := range tbl.columns {
 		if c.Key == key {