fix: restore K&R coding style and correct return value (#75)

- Fix switch-case indentation to follow K&R style (align case labels with switch)
- Replace EXIT_SUCCESS with 0 in non-exit function argparse_help_cb_no_exit()
- EXIT_SUCCESS should only be used with exit() or returned by main()

Fixes #74

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-authored-by: Claude <noreply@anthropic.com>

Author: cofyc

argparse.c

@@ -130,17 +130,17 @@ argparse_options_check(const struct argparse_option *options)
 {
     for (; options->type != ARGPARSE_OPT_END; options++) {
         switch (options->type) {
-            case ARGPARSE_OPT_END:
-            case ARGPARSE_OPT_BOOLEAN:
-            case ARGPARSE_OPT_BIT:
-            case ARGPARSE_OPT_INTEGER:
-            case ARGPARSE_OPT_FLOAT:
-            case ARGPARSE_OPT_STRING:
-            case ARGPARSE_OPT_GROUP:
-                continue;
-            default:
-                fprintf(stderr, "wrong option type: %d", options->type);
-                break;
+        case ARGPARSE_OPT_END:
+        case ARGPARSE_OPT_BOOLEAN:
+        case ARGPARSE_OPT_BIT:
+        case ARGPARSE_OPT_INTEGER:
+        case ARGPARSE_OPT_FLOAT:
+        case ARGPARSE_OPT_STRING:
+        case ARGPARSE_OPT_GROUP:
+            continue;
+        default:
+            fprintf(stderr, "wrong option type: %d", options->type);
+            break;
         }
     }
 }
@@ -383,7 +383,7 @@ argparse_help_cb_no_exit(struct argparse *self,
 {
     (void)option;
     argparse_usage(self);
-    return (EXIT_SUCCESS);
+    return 0;
 }
 
 int