docs(esp_trace): restructure tracing docs with esp_trace as master

Reorganize the tracing documentation so esp_trace is the master
component, with app_trace, SystemView, and Gcov referenced from it.

(cherry picked from commit 6c6490d54c)

docs/en/api-reference/system/esp_trace.rst

@@ -0,0 +1,70 @@
+ESP Trace
+=========
+
+:link_to_translation:`zh_CN:[中文]`
+
+Overview
+--------
+
+The ``esp_trace`` component is the entry point for ESP-IDF tracing. It provides the public tracing API, manages the active trace session, and connects the selected encoder, such as SEGGER SystemView, with the selected transport, such as apptrace.
+
+For a conceptual overview, architecture, and usage guides, see :doc:`/api-guides/tracing/index`.
+
+Application Examples
+--------------------
+
+- :example:`system/esp_trace_custom_library` demonstrates how to integrate an external trace library (encoder) with the ``esp_trace`` core.
+
+API Reference
+-------------
+
+Types
+^^^^^
+
+.. doxygentypedef:: esp_trace_handle_t
+
+.. doxygenstruct:: esp_trace_open_params_t
+    :members:
+
+.. doxygenstruct:: esp_trace_config
+    :members:
+
+.. doxygenenum:: esp_trace_link_types_t
+
+Adapter Types
+^^^^^^^^^^^^^
+
+.. doxygenstruct:: esp_trace_encoder_vtable_t
+    :members:
+
+.. doxygenstruct:: esp_trace_encoder
+    :members:
+
+.. doxygenenum:: esp_trace_transport_cfg_key_t
+
+.. doxygenstruct:: esp_trace_transport_vtable_t
+    :members:
+
+.. doxygenstruct:: esp_trace_transport
+    :members:
+
+Functions
+^^^^^^^^^
+
+.. doxygenfunction:: esp_trace_get_user_params
+
+.. doxygenfunction:: esp_trace_get_active_handle
+
+.. doxygenfunction:: esp_trace_write
+
+.. doxygenfunction:: esp_trace_start
+
+.. doxygenfunction:: esp_trace_stop
+
+.. doxygenfunction:: esp_trace_flush
+
+.. doxygenfunction:: esp_trace_is_host_connected
+
+.. doxygenfunction:: esp_trace_get_link_type
+
+.. doxygenfunction:: esp_trace_panic_handler

docs/en/api-reference/system/index.rst

@@ -9,6 +9,7 @@ System API
     app_image_format
     bootloader_image_format
     app_trace
+    esp_trace
     esp_function_with_shared_stack
     chip_revision
     console