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.

core/registry.c

@@ -0,0 +1,60 @@
+/*
+ * IAMROOT — module registry implementation
+ *
+ * Simple flat array. Resized in chunks of 16. We never expect more
+ * than a few dozen modules, so this is fine.
+ */
+
+#include "registry.h"
+
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define REGISTRY_CHUNK 16
+
+static const struct iamroot_module **g_modules = NULL;
+static size_t g_count = 0;
+static size_t g_cap = 0;
+
+void iamroot_register(const struct iamroot_module *m)
+{
+    if (m == NULL || m->name == NULL) {
+        fprintf(stderr, "[!] iamroot_register: NULL module or unnamed module\n");
+        return;
+    }
+    if (g_count == g_cap) {
+        size_t new_cap = g_cap + REGISTRY_CHUNK;
+        const struct iamroot_module **n =
+            realloc((void *)g_modules, new_cap * sizeof(*g_modules));
+        if (n == NULL) {
+            fprintf(stderr, "[!] iamroot_register: OOM\n");
+            return;
+        }
+        g_modules = n;
+        g_cap = new_cap;
+    }
+    g_modules[g_count++] = m;
+}
+
+size_t iamroot_module_count(void)
+{
+    return g_count;
+}
+
+const struct iamroot_module *iamroot_module_at(size_t i)
+{
+    if (i >= g_count) return NULL;
+    return g_modules[i];
+}
+
+const struct iamroot_module *iamroot_module_find(const char *name)
+{
+    if (name == NULL) return NULL;
+    for (size_t i = 0; i < g_count; i++) {
+        if (strcmp(g_modules[i]->name, name) == 0)
+            return g_modules[i];
+    }
+    return NULL;
+}