feat: /realm in TUI, daemon instance takeover (0.9.16)

Pidfile records instance+port; login restarts the service when the seat
changes. TUI /realm status|login|stop; prompts discourage filler chatter.

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/test_parliament.c

@@ -72,8 +72,10 @@ int main(void) {
 
   char *st = cst_parliament_status_text();
   assert(st && strstr(st, "parliament"));
+  assert(strstr(st, "service"));
   free(st);
   assert(cst_parliament_is_active());
+  assert(cst_parliament_daemon_info(NULL, NULL, 0, NULL) != 0);
 
   test_rmrf(dir);
   puts("test_parliament: OK");