feat(intellij/T39): add has/mirror keywords, id_def rule, extraction_def rule

Baboon.flex: add KW_ID, KW_HAS, KW_MIRROR token rules
Baboon.bnf:
- Add KW_ID, KW_HAS, KW_MIRROR to token declarations
- Add id_def with optional template_head and dto_member body
- Add template_head rule for [T, U, ...] syntax on id_def
- Add extraction_def rule for `has (mirror|contract) <name>`
- Add extraction_def to dto_member and adt_member alternatives
- Wire id_def into main_member
BaboonTokenType.kt: add KW_ID, KW_HAS, KW_MIRROR to BABOON_KEYWORDS
  (covers syntax highlighting and remapIfKeyword softness for field names)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: pshirshov

src/main/grammar/Baboon.bnf

@@ -15,6 +15,7 @@
     // keywords
     KW_DATA      = "data"
     KW_STRUCT    = "struct"
+    KW_ID        = "id"
     KW_ROOT      = "root"
     KW_MODEL     = "model"
     KW_CONTRACT  = "contract"
@@ -37,6 +38,8 @@
     KW_WAS       = "was"
     KW_PRAGMA    = "pragma"
     KW_TYPE      = "type"
+    KW_HAS       = "has"
+    KW_MIRROR    = "mirror"
 
     LBRACE = "{"
     RBRACE = "}"
@@ -96,7 +99,7 @@ include ::= KW_INCLUDE string_literal;
 member ::= main_member | namespace;
 namespace ::= KW_NAMESPACE IDENTIFIER (LBRACE content* RBRACE | LPAREN content* RPAREN);
 
-main_member ::= KW_ROOT? (choice | dto | adt | foreign | contract | service | type_alias);
+main_member ::= KW_ROOT? (choice | dto | id_def | adt | foreign | contract | service | type_alias);
 type_alias ::= KW_TYPE class_name EQUAL type_ref;
 
 class_name ::= IDENTIFIER {
@@ -124,7 +127,15 @@ choice_member_rename ::= COLON KW_WAS LBRACK IDENTIFIER RBRACK;
 
 // dto
 dto ::= KW_DATA class_name member_meta? (LBRACE dto_member* RBRACE | LPAREN dto_member* RPAREN);
-dto_member ::= field_def | parent_def | unfield_def | unparent_def | intersection_def | extended_contract_def;
+dto_member ::= field_def | parent_def | unfield_def | unparent_def | intersection_def | extended_contract_def | extraction_def;
+
+// id (identifier type, M18 / T39) — same shape as dto with optional template-head.
+// template_head carries the type-parameter names: `[T]`, `[K, V]`, etc.
+id_def ::= KW_ID class_name template_head? member_meta? (LBRACE dto_member* RBRACE | LPAREN dto_member* RPAREN);
+template_head ::= LBRACK IDENTIFIER (COMMA IDENTIFIER)* RBRACK;
+
+// extraction clause (T37/T39): `has (mirror | contract) <bare-identifier>`
+extraction_def ::= KW_HAS (KW_MIRROR | KW_CONTRACT) IDENTIFIER;
 
 field_def ::= field_name COLON type_ref field_rename?;
 field_rename ::= KW_WAS field_name;
@@ -144,7 +155,7 @@ extended_contract_def ::= KW_IS non_generic_type_ref;
 
 // adt
 adt ::= KW_ADT class_name member_meta? (LBRACE adt_member* RBRACE | LPAREN adt_member* RPAREN);
-adt_member ::= (dto | contract) | extended_contract_def;
+adt_member ::= (dto | contract) | extended_contract_def | extraction_def;
 
 // foreign
 foreign ::= KW_FOREIGN class_name member_meta? (LBRACE foreign_member* RBRACE | LPAREN foreign_member* RPAREN);

src/main/grammar/Baboon.flex

@@ -37,6 +37,7 @@ BI_TYPE = "bit"|"i08"|"i16"|"i32"|"i64"|"u08"|"u16"|"u32"|"u64"|"f32"|"f64"|"f12
 <YYINITIAL> {
   "data"         { return BaboonTypes.KW_DATA; }
   "struct"       { return BaboonTypes.KW_STRUCT; }
+  "id"           { return BaboonTypes.KW_ID; }
   "root"         { return BaboonTypes.KW_ROOT; }
   "model"        { yybegin(IN_MODEL_NAME); return BaboonTypes.KW_MODEL; }
   "contract"     { return BaboonTypes.KW_CONTRACT; }
@@ -59,6 +60,8 @@ BI_TYPE = "bit"|"i08"|"i16"|"i32"|"i64"|"u08"|"u16"|"u32"|"u64"|"f32"|"f64"|"f12
   "was"          { return BaboonTypes.KW_WAS; }
   "pragma"       { return BaboonTypes.KW_PRAGMA; }
   "type"         { return BaboonTypes.KW_TYPE; }
+  "has"          { return BaboonTypes.KW_HAS; }
+  "mirror"       { return BaboonTypes.KW_MIRROR; }
 
    "{"           { return BaboonTypes.LBRACE; }
    "}"           { return BaboonTypes.RBRACE; }

src/main/kotlin/io/septimalmind/baboon/baboonintellij/psi/BaboonTokenType.kt

@@ -10,10 +10,10 @@ class BaboonTokenType(debugName: String) : IElementType(debugName, BaboonLanguag
 val BABOON_COMMENTS = TokenSet.create(LINE_COMMENT, BLOCK_COMMENT, DOC_COMMENT)
 
 val BABOON_KEYWORDS = TokenSet.create(
-    KW_DATA, KW_STRUCT, KW_ROOT, KW_MODEL, KW_CONTRACT, KW_SERVICE, KW_CHOICE,
+    KW_DATA, KW_STRUCT, KW_ID, KW_ROOT, KW_MODEL, KW_CONTRACT, KW_SERVICE, KW_CHOICE,
     KW_ADT, KW_FOREIGN, KW_VERSION, KW_INCLUDE, KW_NAMESPACE, KW_WITH,
     KW_IS, KW_IN, KW_OUT, KW_ERR, KW_DEF, KW_DERIVED, KW_IMPORT, KW_WITHOUT,
-    KW_WAS, KW_PRAGMA, KW_TYPE
+    KW_WAS, KW_PRAGMA, KW_TYPE, KW_HAS, KW_MIRROR
 )
 
 val OPERATION_SIGNS = TokenSet.create(