Phase 1: module interface + registry + top-level dispatcher

- core/module.h: struct iamroot_module + iamroot_result_t
- core/registry.{h,c}: flat-array module registry with find-by-name
- modules/copy_fail_family/iamroot_modules.{h,c}: bridge layer
  exposing 5 modules (copy_fail, copy_fail_gcm, dirty_frag_esp,
  dirty_frag_esp6, dirty_frag_rxrpc) wired to the absorbed DIRTYFAIL
  detect/exploit functions; df_result_t/iamroot_result_t share numeric
  values intentionally for zero-cost translation
- iamroot.c: top-level CLI dispatcher with --scan / --list / --exploit /
  --mitigate / --cleanup, JSON output, --i-know gate
- Restored modules/copy_fail_family/src/ structure (DIRTYFAIL Makefile
  expects it; the initial flat copy broke that contract)
- Top-level Makefile builds one binary; filters out DIRTYFAIL's
  original dirtyfail.c main so it doesn't conflict with iamroot.c

Verified end-to-end on kctf-mgr (Linux): clean compile, 5 modules
register, --scan --json output ingest-ready, exit codes propagate.

modules/copy_fail_family/iamroot_modules.h

@@ -0,0 +1,28 @@
+/*
+ * copy_fail_family — IAMROOT module registry hooks
+ *
+ * The family currently contains five iamroot_module entries:
+ *
+ *   - copy_fail        (CVE-2026-31431, algif_aead authencesn)
+ *   - copy_fail_gcm    (no CVE, rfc4106(gcm(aes)) variant)
+ *   - dirty_frag_esp   (CVE-2026-43284 v4)
+ *   - dirty_frag_esp6  (CVE-2026-43284 v6)
+ *   - dirty_frag_rxrpc (CVE-2026-43500)
+ *
+ * Defined in iamroot_modules.c, registered into the global registry
+ * by iamroot_register_copy_fail_family() (declared in
+ * core/registry.h).
+ */
+
+#ifndef COPY_FAIL_FAMILY_IAMROOT_MODULES_H
+#define COPY_FAIL_FAMILY_IAMROOT_MODULES_H
+
+#include "../../core/module.h"
+
+extern const struct iamroot_module copy_fail_module;
+extern const struct iamroot_module copy_fail_gcm_module;
+extern const struct iamroot_module dirty_frag_esp_module;
+extern const struct iamroot_module dirty_frag_esp6_module;
+extern const struct iamroot_module dirty_frag_rxrpc_module;
+
+#endif