feat(openthread): use explicit source list for RCP build

components/openthread/srcs_spinel.cmake

@@ -0,0 +1,45 @@
+# SPDX-FileCopyrightText: 2026 Espressif Systems (Shanghai) CO LTD
+# SPDX-License-Identifier: Apache-2.0
+
+# Source files for SPINEL_ONLY mode.
+# Minimal build for host-side spinel communication.
+# Uses explicit whitelist for clarity.
+
+set(private_include_dirs
+    "private_include"
+    "openthread/src"
+    "openthread/src/core"
+    "openthread/src/include"
+    "openthread/src/lib"
+    "openthread/src/lib/hdlc"
+    "openthread/src/lib/spinel"
+)
+
+set(spinel_srcs
+    # ESP spinel sources
+    src/spinel/esp_radio_spinel.cpp
+    src/spinel/esp_radio_spinel_uart_interface.cpp
+    # ESP port (minimal)
+    src/port/esp_openthread_alarm.c
+    src/port/esp_openthread_logging.c
+    # OpenThread spinel library
+    openthread/src/lib/spinel/spinel.c
+    openthread/src/lib/spinel/spinel_buffer.cpp
+    openthread/src/lib/spinel/spinel_decoder.cpp
+    openthread/src/lib/spinel/spinel_encoder.cpp
+    openthread/src/lib/spinel/spinel_helper.cpp
+    openthread/src/lib/spinel/radio_spinel.cpp
+    openthread/src/lib/spinel/spinel_driver.cpp
+    openthread/src/lib/spinel/logger.cpp
+    # OpenThread HDLC library
+    openthread/src/lib/hdlc/hdlc.cpp
+    # OpenThread platform library
+    openthread/src/lib/platform/exit_code.c
+    # OpenThread core (minimal)
+    openthread/src/core/api/error_api.cpp
+    openthread/src/core/api/logging_api.cpp
+    openthread/src/core/common/error.cpp
+    openthread/src/core/common/log.cpp
+    openthread/src/core/common/string.cpp
+    openthread/src/core/mac/mac_frame.cpp
+)