use junctions for base-apps icon paths instead of duplicate files

Create Windows junctions at root pointing to src/main/assets/:
  mklink /J icons src\main\assets\icons
  mklink /J scripts src\main\assets\scripts
  mklink /J ui src\main\assets\ui

This avoids duplicating files while allowing base-apps manifest
paths like ../../icons/ to resolve correctly.

.gitignore

@@ -17,10 +17,11 @@ test_*.log
 *_hierarchy.json
 recorded_actions.json
 
-# Duplicate asset folders (use src/main/assets/ instead)
-/icons/
-/scripts/
-/ui/
+# Junctions to src/main/assets/ for base-apps testing
+# Create with: mklink /J icons src\main\assets\icons (etc.)
+/icons
+/scripts
+/ui
 
 # Sandbox data created during testing
 /src/main/assets/sandbox_data/