refactor: drop the params pane's Help section

Its only row was an About button no handler ever dispatched, so the section was
two rows of dead chrome. Removed from the Main node's param sync, and pruned on
load so saves that already carry the pair lose it too — matching how the retired
Node Color params are handled a few lines up.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

 src/project.rs | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/project.rs b/src/project.rs
index 4cb8760..09c5595 100644
--- a/src/project.rs
+++ b/src/project.rs
@@ -401,8 +401,9 @@ impl State {
         ensure_param(main_node, "Background Color", "color", &color_to_hex(vp_bg_color), &[], None, None, None);
         ensure_param(main_node, "Grid Color", "color", &color_to_hex(vp_grid_color), &[], None, None, None);
 
-        ensure_param(main_node, "Help", "section", "", &[], None, None, None);
-        ensure_param(main_node, "About", "button", "", &[], None, None, None);
+        // The Help section is retired — its only row was an About button nothing
+        // dispatched. Drop it from older saves too.
+        main_node.params.retain(|p| !matches!(p.name.as_str(), "Help" | "About"));
 
         // Boolean settings and pane-visibility items render as toggles. Older
         // saves stored these as choice dropdowns / buttons; retype them and