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/formfields.go

@@ -9,6 +9,9 @@ type FormFields struct {
 	Primary        string
 	Secondary      string
 	ReadOnly       bool
+	HasStatus      bool
+	Status         ProjectLifecycle
+	ResponsibleID  string
 }
 
 // KindHeading returns a short label for the detail pane header.
@@ -80,6 +83,21 @@ func FormFieldsFromRaw(kind Kind, raw map[string]any) FormFields {
 			Primary: strRaw(raw, "title"), Secondary: strRaw(raw, "description"),
 			ReadOnly: true,
 		}
+	case KindProject:
+		title := strRaw(raw, "title")
+		if title == "" {
+			title = strRaw(raw, "name")
+		}
+		return FormFields{
+			PrimaryLabel:   "Title",
+			SecondaryLabel: "Description",
+			Primary:        title,
+			Secondary:      strRaw(raw, "description"),
+			ReadOnly:       false,
+			HasStatus:      true,
+			Status:         ProjectStatusFromAny(raw["status"]),
+			ResponsibleID:  ResponsibleIDFromRaw(raw),
+		}
 	default:
 		title := strRaw(raw, "title")
 		if title == "" {
@@ -109,7 +127,19 @@ func strRaw(m map[string]any, key string) string {
 	return fmt.Sprint(m[key])
 }
 
-// IsDocumentKind is true when the right pane should show file content, not a form.
+// ResponsibleIDFromRaw extracts the project responsible user id from API detail.
+func ResponsibleIDFromRaw(raw map[string]any) string {
+	if id := strRaw(raw, "responsibleId"); id != "" {
+		return id
+	}
+	resp, ok := raw["responsible"].(map[string]any)
+	if !ok {
+		return ""
+	}
+	return strRaw(resp, "id")
+}
+
+// IsDocumentKind is true when the right pane should show rendered preview content, not an editable form.
 func IsDocumentKind(kind Kind) bool {
-	return kind == KindFile
+	return kind == KindFile || kind == KindMail
 }