i2s_audio_duplex: validate use_apll against SoC capability

APLL clock source is only available on ESP32, ESP32-S2, and ESP32-P4.
Previously use_apll: true was silently ignored on ESP32-S3 (the ifdef
guard compiled it out). Now FINAL_VALIDATE raises an error with a clear
message listing supported variants.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: n-IA-hane

esphome/components/i2s_audio_duplex/__init__.py

@@ -240,6 +240,14 @@ def _final_validate(config):
             f"task_core={task_core} not available on {variant} (single-core SoC)"
         )
 
+    # APLL is only available on ESP32, ESP32-S2, and ESP32-P4
+    APLL_VARIANTS = {VARIANT_ESP32, VARIANT_ESP32S2, VARIANT_ESP32P4}
+    if config.get(CONF_USE_APLL, False) and variant not in APLL_VARIANTS:
+        raise cv.Invalid(
+            f"use_apll is not supported on {variant}. "
+            f"APLL clock source is only available on ESP32, ESP32-S2, and ESP32-P4."
+        )
+
     # Cross-component validation: check for AEC conflict with intercom_api
     from esphome.core import CORE
     full_config = CORE.config or {}