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.rterm.c

@@ -0,0 +1,34 @@
+#include "rterm.h"
+
+void before_cursor_move(rterm_t *rterm) {
+    // printf("Before cursor update: %d:%d\n",rterm->cursor.x,rterm->cursor.y);
+}
+void after_cursor_move(rterm_t *rterm) {
+
+    // rterm->cursor.x++;
+}
+void before_key_press(rterm_t *rterm) {
+
+    // if(rterm->key.c == 65 && rterm->key.escape){
+    //     rterm->key.c = 66;
+    //}
+}
+void tick(rterm_t *rt) {
+    static char status_text[1024];
+    status_text[0] = 0;
+    sprintf(status_text, "\rp:%d:%d | k:%c:%d | i:%ld ", rt->cursor.x + 1, rt->cursor.y + 1, rt->key.c == 0 ? '0' : rt->key.c, rt->key.c,
+            rt->iterations);
+    rt->status_text = status_text;
+}
+
+int main() {
+    rterm_t rt;
+    rterm_init(&rt);
+    rt.show_cursor = true;
+    rt.before_key_press = before_key_press;
+    rt.before_cursor_move = before_cursor_move;
+    rt.after_cursor_move = after_cursor_move;
+    rt.tick = tick;
+    rterm_loop(&rt);
+    return 0;
+}