Fix RMLui detection and graceful Chili fallback

Fixed two critical issues with RMLui integration:

1. **Incorrect RMLui detection**:
   - api_sb_rmlui.lua:21 was checking `Spring.RmlUi` instead of `RmlUi`
   - view.lua:6 had the same issue
   - The global `RmlUi` is the correct API (matches rml_setup2.lua and dbg_dev_console_rmlui.lua)

2. **Broken Chili fallback**:
   - rmlui_components.lua was loaded by IncludeDir during Chili fallback
   - It tried to extend RmlUiEditorBase without checking if it exists
   - Added guards to return early if RMLui base classes aren't loaded

This ensures SpringBoard gracefully falls back to Chili UI when RMLui is not available.

Author: claude

LuaUI/widgets/api_sb_rmlui.lua

@@ -18,14 +18,14 @@ local initialized = false
 
 function widget:Initialize()
     -- Check if RmlUi is available
-    if not Spring.RmlUi then
+    if not RmlUi then
         Spring.Log("SpringBoard RmlUi", LOG.WARNING, "RmlUi not available in this Spring engine version")
         Spring.Log("SpringBoard RmlUi", LOG.WARNING, "Falling back to Chili UI (engine needs BAR 105.1.1+ for RmlUi)")
         widgetHandler:RemoveWidget(self)
         return false
     end
 
-    rmlui = Spring.RmlUi
+    rmlui = RmlUi
     initialized = true
 
     Spring.Log("SpringBoard RmlUi", LOG.NOTICE, "RmlUi Framework initialized")

scen_edit/view/rmlui_components.lua

@@ -5,6 +5,11 @@
 -- ALL EDITORS extend RmlUiEditorBase and use the generic template
 -- They differ only in which fields they add programmatically
 
+-- Only define these classes if RmlUi infrastructure is loaded
+if not RmlUiEditorBase then
+    return
+end
+
 -- General Windows
 RmlUiScenarioInfoView = RmlUiEditorBase:extends{}
 function RmlUiScenarioInfoView:init()
@@ -175,6 +180,10 @@ function RmlUiCustomWindow:init()
 end
 
 -- Dialog Variants - all use RmlUiFileDialog (100% programmatic)
+if not RmlUiFileDialog then
+    return
+end
+
 RmlUiImportFileDialog = RmlUiFileDialog:extends{}
 function RmlUiImportFileDialog:init(opts)
     opts = opts or {}

scen_edit/view/view.lua

@@ -3,7 +3,7 @@ View = LCS.class{}
 function View:init()
     -- Try to initialize RmlUi if available
     self.useRmlUi = false
-    if Spring.RmlUi then
+    if RmlUi then
         -- Load RmlUi infrastructure
         SB.Include(Path.Join(SB.DIRS.SRC, 'view/rmlui_manager.lua'))
         SB.Include(Path.Join(SB.DIRS.SRC, 'view/rmlui_builder.lua'))