feat: self-hosting progress - Nim backend, parser fixes, 64 struct fields, 13/14 modules check

tests/test_parse_ast.nim

@@ -0,0 +1,16 @@
+import "../src/lexer", "../src/parser", "../src/ast", "../src/token"
+import std/os
+
+let source = readFile("../_selfhost/src/ast.bux")
+let lexRes = tokenize(source, "ast.bux")
+echo "Tokens: ", lexRes.tokens.len
+echo "Errors: ", lexRes.hasErrors
+let res = parse(lexRes.tokens, "ast.bux")
+if res.module == nil:
+  echo "Parse failed, diagnostics: ", res.diagnostics.len
+  for d in res.diagnostics:
+    echo "  ", d.message
+else:
+  echo "Parsed OK, items: ", res.module.items.len
+  for i, decl in res.module.items:
+    echo "Decl ", i, " kind=", decl.kind, " name=", decl.declFuncName