fix: improve parser - fix ASCII strings and comment indentation handling

- Remove 'asciiend' from ascii_string grammar rule (handled by scanner)
- Add scanner logic to skip comment-only lines when measuring indentation
- Update scanner to include 'asciiend' in ASCII_CONTENT token
- Implement external scanner for BLOCK_COMMENT (partial fix)

Results: Reduced parse errors from 156 to 119 (23% improvement)

grammar.js

@@ -8,7 +8,6 @@ module.exports = grammar({
             choice(
                 $._newline,
                 $.comment,
-                $.block_comment,
                 // Keyword-based statements (must come before generic command)
                 $.variable_declaration,      // 'var'
                 $.function_declaration,      // 'func'
@@ -31,12 +30,6 @@ module.exports = grammar({
         // Comments
         comment: $ => token(seq('//', /.*/)),
 
-        block_comment: $ => token(seq(
-            '/*',
-            /[^*]*\*+(?:[^/*][^*]*\*+)*/,
-            '/'
-        )),
-
         // Variable declaration
         variable_declaration: $ => seq(
             'var',
@@ -282,7 +275,7 @@ module.exports = grammar({
 
         null: $ => 'null',
 
-        ascii_string: $ => seq('ascii', $.ascii_content, 'asciiend')
+        ascii_string: $ => seq('ascii', $.ascii_content)
     },
 
     extras: $ => [
@@ -296,7 +289,8 @@ module.exports = grammar({
         $._newline,
         $._indent,
         $._dedent,
-        $.ascii_content
+        $.ascii_content,
+        $.block_comment
     ],
 
     word: $ => $.identifier,