fix(p8h-core): escape log paths, fail closed on identity activation, tidy server gate

- A6: escape attacker-controlled file paths and the receive root in log
  lines (file_receive, server, protocol DEBUG) with output_escape()
- A8: identity_set_active() returns bool and fails closed when a requested
  usermap/groupmap cannot be deep-copied; handler refuses the connection
- remove the const cast and duplicate super_mode clamp from
  server_module_gate via an explicit override the handler applies once
- release the identity snapshot on the queue_create failure path
- refactor identity_parse_copy_as to a single cleanup tail and drop the
  duplicated group error format specifier

src/shared/protocol.c

@@ -459,10 +459,14 @@ static char* protocol_receive_str_impl(ProtocolSession* session, bool redact) {
     return NULL;
   }
   data[size] = '\0';
-  if (redact)
+  if (redact) {
     log_debug_message(LOG_DEBUG_PROTO, "Received String: <redacted>");
-  else
-    log_debug_message(LOG_DEBUG_PROTO, "Received String: %s", data);
+  } else {
+    char* escaped_data = output_escape(data, log_get_8_bit_output());
+    log_debug_message(LOG_DEBUG_PROTO, "Received String: %s",
+                      escaped_data ? escaped_data : "<allocation failed>");
+    free(escaped_data);
+  }
   return data;
 }