feat(option): allow case None on nullable pointers

None stays a keyword literal; the pattern parser already produced MatchSingleton, and the nullable-pointer match now treats it as the Nil branch. LSP colors None as a keyword.

App/lib/core/Gen/MatchGenMixin.vp

@@ -301,6 +301,7 @@ novirtual class MatchGenMixin:
             if vnm is None: return 0
             if string.strcmp(vnm, "Some") == 0: return 1
             if string.strcmp(vnm, "Nil") == 0: return 2
+        if k == ast.ASTKind.MatchSingleton: return 2
         return 0
 
     def _match_has_opt_pattern(self, node: ast.Match*) -> int:

App/lib/lsp/LspSemantic.vp

@@ -535,6 +535,8 @@ def _LexStream(pool: memhub.MemManager*,
             typ = ST_NUMBER
         elif tok.type == ast.TokenType.Name and tok.str_val is not None and string.strcmp(tok.str_val, "own") == 0:
             typ = ST_KEYWORD
+        elif tok.type == ast.TokenType.Name and tok.str_val is not None and string.strcmp(tok.str_val, "None") == 0:
+            typ = ST_KEYWORD
         elif tok.type == ast.TokenType.Name and tok.str_val is not None and string.strcmp(tok.str_val, "Some") == 0:
             typ = ST_CLASS
         elif tok.type == ast.TokenType.Name and tok.str_val is not None and string.strcmp(tok.str_val, "Nil") == 0: