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/nav.go

@@ -1,5 +1,7 @@
 package model
 
+import "strings"
+
 // ListSpec tells the fetch layer what to load when a nav leaf is active.
 type ListSpec struct {
 	Subject   Subject
@@ -24,6 +26,7 @@ type NavTree struct {
 	expanded map[string]bool
 	cursor   int
 	visible  []string
+	filter   string
 }
 
 // DefaultNavTree returns the OnlyOffice module tree (static skeleton).
@@ -42,15 +45,11 @@ func DefaultNavTree() *NavTree {
 		}
 	}
 
-	add("projects", "Projects", "", true, nil)
-	add("projects.browse", "Browse", "projects", true, nil)
-	add("projects.browse.all", "All projects", "projects.browse", false, &ListSpec{Subject: SubjectProjects})
-	add("projects.browse.tasks", "All tasks", "projects.browse", false, &ListSpec{Subject: SubjectTasks})
-	add("projects.dynamic", "By project", "projects", true, nil)
+	add("projects", "Projects", "", false, &ListSpec{Subject: SubjectProjects})
+	add("tasks", "Tasks", "", false, &ListSpec{Subject: SubjectTasks})
+	add("projects.dynamic", "By project", "", true, nil)
 
-	add("calendar", "Calendar", "", true, nil)
-	add("calendar.cals", "Calendars", "calendar", false, &ListSpec{Subject: SubjectCalendars})
-	add("calendar.events", "Events", "calendar", false, &ListSpec{Subject: SubjectEvents})
+	add("calendar", "Calendar", "", false, &ListSpec{Subject: SubjectCalendar})
 
 	add("crm", "CRM", "", true, nil)
 	add("crm.contacts", "Contacts", "crm", false, &ListSpec{Subject: SubjectContacts})
@@ -185,20 +184,66 @@ func (t *NavTree) Activate() (*ListSpec, bool) {
 	return nil, false
 }
 
+func (t *NavTree) SetFilter(query string) {
+	t.filter = strings.ToLower(strings.TrimSpace(query))
+	t.rebuildVisible()
+}
+
+func (t *NavTree) ClearFilter() {
+	t.filter = ""
+	t.rebuildVisible()
+}
+
+func (t *NavTree) FilterQuery() string { return t.filter }
+
+func (t *NavTree) nodeLabelMatches(id string) bool {
+	if t.filter == "" {
+		return true
+	}
+	n, ok := t.nodes[id]
+	if !ok {
+		return false
+	}
+	return strings.Contains(strings.ToLower(n.Label), t.filter)
+}
+
+func (t *NavTree) hasMatchingDescendant(id string) bool {
+	for _, child := range t.children[id] {
+		if t.nodeLabelMatches(child) || t.hasMatchingDescendant(child) {
+			return true
+		}
+	}
+	return false
+}
+
+func (t *NavTree) visibleUnderFilter(id string) bool {
+	if t.filter == "" {
+		return true
+	}
+	return t.nodeLabelMatches(id) || t.hasMatchingDescendant(id)
+}
+
 func (t *NavTree) rebuildVisible() {
 	t.visible = t.visible[:0]
-	var walk func(id string, depth int)
-	walk = func(id string, depth int) {
+	var walk func(id string)
+	walk = func(id string) {
+		if !t.visibleUnderFilter(id) {
+			return
+		}
 		t.visible = append(t.visible, id)
-		if !t.expanded[id] {
+		expanded := t.expanded[id]
+		if t.filter != "" && t.hasMatchingDescendant(id) {
+			expanded = true
+		}
+		if !expanded {
 			return
 		}
 		for _, child := range t.children[id] {
-			walk(child, depth+1)
+			walk(child)
 		}
 	}
 	for _, root := range t.roots {
-		walk(root, 0)
+		walk(root)
 	}
 	if t.cursor >= len(t.visible) {
 		t.cursor = len(t.visible) - 1