[core] Remove deprecated esphome::RingBuffer alias (#20390)

esphome/core/ring_buffer.h

@@ -1,22 +0,0 @@
-#pragma once
-
-#ifdef USE_ESP32
-
-// Deprecated: include "esphome/components/ring_buffer/ring_buffer.h" and use
-// esphome::ring_buffer::RingBuffer. This shim will be removed in 2026.11.0.
-#if __has_include("esphome/components/ring_buffer/ring_buffer.h")
-#include "esphome/components/ring_buffer/ring_buffer.h"
-#else
-#error \
-    "esphome/components/ring_buffer/ring_buffer.h not found. Add 'ring_buffer' to your component's AUTO_LOAD list to use esphome::ring_buffer::RingBuffer."
-#endif
-#include "esphome/core/helpers.h"  // for ESPDEPRECATED
-
-namespace esphome {
-
-using RingBuffer ESPDEPRECATED("Use esphome::ring_buffer::RingBuffer instead. Removed in 2026.11.0.",
-                               "2026.5.0") = ring_buffer::RingBuffer;
-
-}  // namespace esphome
-
-#endif

esphome/writer.py

@@ -212,14 +212,11 @@ BUILD_INFO_DATA_H_TARGET = "esphome/core/build_info_data.h"
 BUILD_INFO_DATA_CPP_TARGET = "esphome/core/build_info_data.cpp"
 ENTITY_TYPES_H_TARGET = "esphome/core/entity_types.h"
 # Headers that must not be included bare from esphome.h or the clang-tidy
-# all-headers file: X-macro files, headers main.cpp includes itself, and
-# deprecated headers that only resolve when their new component is loaded.
+# all-headers file: X-macro files and headers main.cpp includes itself.
 ESPHOME_H_EXCLUDE = {
     Path(ENTITY_TYPES_H_TARGET),
     # main.cpp includes it after defining esphome_controllers()
     Path("esphome/core/controller_dispatch.h"),
-    # moved to components/ring_buffer/, removed in 2026.11.0
-    Path("esphome/core/ring_buffer.h"),
     # build machinery, not user API
     Path("esphome/core/pch_prefix.h"),
 }