[refactor] Refactor offload code to multi-chunk.

nanovllm/layers/attention.py

@@ -123,8 +123,7 @@ class Attention(nn.Module):
         lse_acc = None
 
         # Load previous KV from CPU using Compute/Prefetch region
-        # Note: context.offload_engine is actually HybridKVCacheManager
-        kvcache_manager = context.offload_engine
+        kvcache_manager = context.kvcache_manager
         seq = context.chunked_seq if hasattr(context, 'chunked_seq') else None
 
         if kvcache_manager is not None and seq is not None and self.layer_id >= 0:
@@ -215,7 +214,7 @@ class Attention(nn.Module):
         # q shape: [batch_size, num_heads, head_dim] (single decode token per sequence)
         q_batched = q.unsqueeze(1)  # [batch, 1, heads, dim]
 
-        kvcache_manager = context.offload_engine
+        kvcache_manager = context.kvcache_manager
         seq = context.chunked_seq
 
         # Get all CPU blocks for this sequence