grammar.js를 parser 기준 규칙으로 정합화

grammar.js

@@ -1,5 +1,5 @@
 // Minimal Tree-sitter grammar for Ferro syntax highlighting in Zed.
-// This intentionally models lexical structure rather than full Ferro semantics.
+// `parser.c` is normative; this file is the editor-copy.
 
 module.exports = grammar({
   name: "ferro",
@@ -10,6 +10,8 @@ module.exports = grammar({
 
   rules: {
     source_file: $ => repeat(choice(
+      $.unit_decl,
+      $.import_decl,
       $.line_comment,
       $.block_comment,
       $.string_literal,
@@ -25,6 +27,11 @@ module.exports = grammar({
 
     line_comment: _ => token(seq("//", /[^\n]*/)),
 
+    unit_decl: $ => seq("unit", $.dotted_identifier, ";"),
+
+    import_decl: $ => seq("import", $.dotted_identifier,
+      optional(seq("as", $.identifier)), ";"),
+
     // Ferro block comments may nest. Keeping this rule recursive makes syntax
     // highlighting follow the compiler lexer instead of flattening nested /* */.
     block_comment: $ => seq(
@@ -92,9 +99,11 @@ module.exports = grammar({
       "+=", "-=", "*=", "/=", "%=", "&=", "|=", "^=",
       "==", "!=", "<=", ">=", "<<", ">>", "->", "=>", "..",
       "+%", "-%", "*%",
-      "+", "-", "*", "/", "%", "=", "<", ">", "&", "|", "^", "~", "!", "?",
+      "+", "-", "*", "/", "%", "=", "<", ">", "&", "|", "^", "!", "?",
     )),
 
+    dotted_identifier: _ => /[A-Za-z_][A-Za-z0-9_]*(\.[A-Za-z_][A-Za-z0-9_]*)*/,
+
     punctuation: _ => token(choice(
       "(", ")", "{", "}", "[", "]", ",", ";", ":", ".",
     )),