fix(esp-tls): address MR review comments for SE PSA driver

- esp_tls_mbedtls: require cert when PSA-backed server/client key is set
- esp_tls_mbedtls: drop redundant pk_init/x509_crt_init (calloc handles it)
- psa SE driver: copy callbacks/opaque_key by value (no lifetime coupling)
- psa SE driver: replace atomic CAS with simple null check on register
- psa SE driver: use sig_len from sign callback with bounds validation
- psa SE driver: validate pubkey_len returned by export_pubkey callback
- psa SE driver: check hash sub-alg in RSA PKCS1V15 branch of validate_request
- psa SE driver: align secure_element_register_callbacks doc with value-copy impl
- esp_https_server: initialize server_key in HTTPD_SSL_CONFIG_DEFAULT
- mbedtls: move SECURE_ELEMENT_DRIVER_ENABLED to esp_config.h for parity
  with ESP_ECDSA_DRIVER_ENABLED; drop target_compile_definitions
- docs: fix esp_tls_cfg_t -> esp_http_client_config_t cross-reference
- docs: check psa_import_key() status in ESP-TLS PSA example
- hints/error_output: point at CONFIG_MBEDTLS_SECURE_ELEMENT_DRIVER_ENABLED

(cherry picked from commit 08b567ef3b)

docs/en/api-reference/protocols/esp_http_client.rst

@@ -36,7 +36,7 @@ To allow ESP HTTP client to take full advantage of persistent connections, one s
 Use Secure Element (ATECC608) for TLS
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-A secure element (ATECC608) can be used for the underlying TLS connection in the HTTP client connection via the PSA Crypto opaque driver interface. Please refer to the **ATECC608A (Secure Element) with ESP-TLS** section in the :doc:`ESP-TLS documentation </api-reference/protocols/esp_tls>` for details on setting up the PSA key. Then configure the HTTP client to use the secure element via the ``client_key`` field in :cpp:type:`esp_tls_cfg_t`:
+A secure element (ATECC608) can be used for the underlying TLS connection in the HTTP client connection via the PSA Crypto opaque driver interface. Please refer to the **ATECC608A (Secure Element) with ESP-TLS** section in the :doc:`ESP-TLS documentation </api-reference/protocols/esp_tls>` for details on setting up the PSA key. Then configure the HTTP client to use the secure element via the ``client_key`` field in :cpp:type:`esp_http_client_config_t`:
 
 .. code-block:: c
 

docs/en/api-reference/protocols/esp_tls.rst

@@ -255,8 +255,13 @@ To enable the secure element support, and use it in your project for TLS connect
        };
 
        psa_key_id_t psa_key_id;
-       psa_import_key(&key_attr, (const uint8_t *)&opaque_key,
-                      sizeof(opaque_key), &psa_key_id);
+       psa_status_t status = psa_import_key(&key_attr, (const uint8_t *)&opaque_key,
+                                            sizeof(opaque_key), &psa_key_id);
+       if (status != PSA_SUCCESS) {
+           /* Handle error - typically means the SE callbacks are not registered
+            * or the attributes are invalid. */
+           return;
+       }
 
        /* Configure ESP-TLS to use the PSA key */
        esp_key_config_t key_config = {

docs/zh_CN/api-reference/protocols/esp_http_client.rst

@@ -35,7 +35,7 @@ HTTP 基本请求
 为 TLS 使用安全元件 (ATECC608)
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-安全元件 (ATECC608) 可通过 PSA Crypto 不透明驱动接口用于 HTTP 客户端连接中的底层 TLS 连接。有关设置 PSA 密钥的详细内容，请参考 :doc:`ESP-TLS 文档 </api-reference/protocols/esp_tls>` 中的 **ESP-TLS 中的 ATECC608A（安全元件）** 小节。然后通过 :cpp:type:`esp_tls_cfg_t` 中的 ``client_key`` 字段配置 HTTP 客户端使用安全元件：
+安全元件 (ATECC608) 可通过 PSA Crypto 不透明驱动接口用于 HTTP 客户端连接中的底层 TLS 连接。有关设置 PSA 密钥的详细内容，请参考 :doc:`ESP-TLS 文档 </api-reference/protocols/esp_tls>` 中的 **ESP-TLS 中的 ATECC608A（安全元件）** 小节。然后通过 :cpp:type:`esp_http_client_config_t` 中的 ``client_key`` 字段配置 HTTP 客户端使用安全元件：
 
 .. code-block:: c
 

docs/zh_CN/api-reference/protocols/esp_tls.rst

@@ -255,8 +255,12 @@ ESP-TLS 支持通过 PSA Crypto 不透明驱动接口在 ESP32 系列芯片上
        };
 
        psa_key_id_t psa_key_id;
-       psa_import_key(&key_attr, (const uint8_t *)&opaque_key,
-                      sizeof(opaque_key), &psa_key_id);
+       psa_status_t status = psa_import_key(&key_attr, (const uint8_t *)&opaque_key,
+                                            sizeof(opaque_key), &psa_key_id);
+       if (status != PSA_SUCCESS) {
+           /* 处理错误 - 通常表示安全元件回调未注册或属性无效。 */
+           return;
+       }
 
        /* 配置 ESP-TLS 使用 PSA 密钥 */
        esp_key_config_t key_config = {