refactor: restructure core module into domain-driven packages with 2672 insertions and 2220 deletions

Splits monolithic core module into bounded contexts: identity, billing, and notification domains. Moves entity definitions, repository interfaces, and service implementations into separate packages. Updates import paths across 25 files to align with new package structure. Removes cross-domain coupling by extracting shared value objects into a common package.

.backup.1.rargs.h

@@ -0,0 +1,58 @@
+#include <stdio.h>
+#ifndef RLIB_RARGS_H
+#define RLIB_RARGS_H
+#include <string.h>
+#include <stdlib.h>
+#include <stdbool.h>
+
+bool rargs_isset(int argc, char *argv[], char *key) {
+
+    for (int i = 0; i < argc; i++) {
+        if (!strcmp(argv[i], key)) {
+            return true;
+        }
+    }
+    return false;
+}
+
+char *rargs_get_option_string(int argc, char *argv[], char *key, const char *def) {
+
+    for (int i = 0; i < argc; i++) {
+        if (!strcmp(argv[i], key)) {
+            if (i < argc - 1) {
+                return argv[i + 1];
+            }
+        }
+    }
+    return (char *)def;
+}
+
+int rargs_get_option_int(int argc, char *argv[], char *key, int def) {
+
+    for (int i = 0; i < argc; i++) {
+        if (!strcmp(argv[i], key)) {
+            if (i < argc - 1) {
+                return atoi(argv[i + 1]);
+            }
+        }
+    }
+    return def;
+}
+
+bool rargs_get_option_bool(int argc, char *argv[], char *key, bool def) {
+
+    for (int i = 0; i < argc; i++) {
+        if (!strcmp(argv[i], key)) {
+            if (i < argc - 1) {
+                if (!strcmp(argv[i + 1], "false"))
+                    return false;
+                if (!strcmp(argv[i + 1], "0"))
+                    return false;
+                return true;
+            }
+        }
+    }
+
+    return def;
+}
+#endif