[esp32] Set UV_CACHE_DIR inside data dir so Clean All clears it (#13888)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

esphome/components/esp32/__init__.py

@@ -1026,6 +1026,10 @@ async def to_code(config):
             Path(__file__).parent / "iram_fix.py.script",
         )
 
+    # Set the uv cache inside the data dir so "Clean All" clears it.
+    # Avoids persistent corrupted cache from mid-stream download failures.
+    os.environ["UV_CACHE_DIR"] = str(CORE.relative_internal_path(".uv_cache"))
+
     if conf[CONF_TYPE] == FRAMEWORK_ESP_IDF:
         cg.add_platformio_option("framework", "espidf")
         cg.add_build_flag("-DUSE_ESP_IDF")