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/model/project_status.go

@@ -0,0 +1,85 @@
+package model
+
+// ProjectLifecycle is the OnlyOffice project status string accepted by the API.
+type ProjectLifecycle string
+
+const (
+	ProjectLifecycleOpen   ProjectLifecycle = "open"
+	ProjectLifecyclePaused ProjectLifecycle = "paused"
+	ProjectLifecycleClosed ProjectLifecycle = "closed"
+)
+
+// ProjectStatusFromAny maps API status (int or string) to a lifecycle value.
+func ProjectStatusFromAny(v any) ProjectLifecycle {
+	switch x := v.(type) {
+	case string:
+		switch ProjectLifecycle(x) {
+		case ProjectLifecycleOpen, ProjectLifecyclePaused, ProjectLifecycleClosed:
+			return ProjectLifecycle(x)
+		}
+	case float64:
+		return projectStatusFromInt(int(x))
+	case int:
+		return projectStatusFromInt(x)
+	case int64:
+		return projectStatusFromInt(int(x))
+	}
+	return ProjectLifecycleOpen
+}
+
+func projectStatusFromInt(n int) ProjectLifecycle {
+	switch n {
+	case 1:
+		return ProjectLifecyclePaused
+	case 2:
+		return ProjectLifecycleClosed
+	default:
+		return ProjectLifecycleOpen
+	}
+}
+
+// ProjectStatusLabel returns a short UI label for list cells.
+func ProjectStatusLabel(raw map[string]any) string {
+	if raw == nil {
+		return "Open"
+	}
+	return ProjectStatusFromAny(raw["status"]).Label()
+}
+
+// ProjectIsOpen is true when the project is not closed.
+func ProjectIsOpen(raw map[string]any) bool {
+	if raw == nil {
+		return true
+	}
+	return ProjectStatusFromAny(raw["status"]) != ProjectLifecycleClosed
+}
+
+// Label returns a human-readable status name.
+func (s ProjectLifecycle) Label() string {
+	switch s {
+	case ProjectLifecycleClosed:
+		return "Closed"
+	case ProjectLifecyclePaused:
+		return "Paused"
+	default:
+		return "Open"
+	}
+}
+
+// ToggleOpenClosed flips between open and closed (paused maps to closed on toggle).
+func (s ProjectLifecycle) ToggleOpenClosed() ProjectLifecycle {
+	if s == ProjectLifecycleClosed {
+		return ProjectLifecycleOpen
+	}
+	return ProjectLifecycleClosed
+}
+
+// Next cycles open → closed → open for keyboard toggling.
+func (s ProjectLifecycle) Next() ProjectLifecycle {
+	return s.ToggleOpenClosed()
+}
+
+// Prev cycles closed → open → closed.
+func (s ProjectLifecycle) Prev() ProjectLifecycle {
+	return s.ToggleOpenClosed()
+}