Adjust context window allocation logic based on memory tiers in `apple_silicon.py`

src/voice_dialogue/utils/apple_silicon.py

@@ -216,11 +216,11 @@ def get_optimal_llama_cpp_config() -> Dict[str, int]:
     
     # 根据内存大小调整上下文窗口
     if chip_info.memory_gb >= 32:
-        n_ctx = 8192
-    elif chip_info.memory_gb >= 16:
         n_ctx = 4096
-    else:
+    elif chip_info.memory_gb >= 16:
         n_ctx = 2048
+    else:
+        n_ctx = 1024
     
     return {
         'n_threads': n_threads,