fix: wrap ISC alias definitions in AliasDef; harden the normalizer on raw leaves

Two more ISC-only breaks, both invisible on .imp installs:

- NodeAdapter stored alias values as bare items. The interpreter
  resolves aliases through AliasDef#data and feeds it to
  Item.try_convert — a bare Any hands it Any#data, an Array, and every
  library-dependent map dies with 'Wrong type Array' the moment
  locate() resolves a library to libs/*.isc instead of a legacy .iml.
- Normalizer#normalize_meta_field assumed Hash entries; empty metadata
  blocks carry a bare Parslet::Slice. scalar() also learns the {raw:
} string form the grammar emits for some metadata fields.

Author: ronaldtse

lib/interscript/isc/node_adapter.rb

@@ -55,7 +55,10 @@ def build_tests
 
       def build_aliases
         @isc_doc[:aliases].each_with_object({}) do |a, h|
-          h[a[:name].to_sym] = convert_item(a[:value])
+          # The runtime resolves aliases through AliasDef#data (see
+          # Interpreter::Stage#build_item); a bare item here hands it a
+          # raw Array once Any#data unrolls.
+          h[a[:name].to_sym] = Interscript::Node::AliasDef.new(a[:name].to_sym, convert_item(a[:value]))
         end
       end
 

lib/interscript/isc/normalizer.rb

@@ -42,6 +42,8 @@ def scalar(node)
           Array(node[:string]).map { |part| part.is_a?(Hash) ? part[:char].to_s : part.to_s }.join
         elsif node.key?(:identifier)
           node[:identifier].to_s
+        elsif node.key?(:raw)
+          node[:raw].to_s
         else
           node
         end
@@ -71,7 +73,7 @@ def normalize_block(block)
       # {field_name: {identifier: "authority"}, field_value: {string: [...]}}
       # becomes {authority: "BGN-PCGN"}.
       def normalize_meta_field(field)
-        return field unless field.key?(:field_name)
+        return field unless field.is_a?(Hash) && field.key?(:field_name)
 
         name = scalar(field[:field_name]).to_sym
         value = field.key?(:field_block) ? field[:field_block] : scalar(field[:field_value])