pub fn encode_tile(layers: &[ColumnarLayer]) -> Result<Vec<u8>>Expand description
Encode a full tile payload (one or more layers) with the layer frame.
Always emits the aligned frame (ALIGNED_FRAME_FLAG set): each
layer’s IPC stream is preceded by zero padding to an 8-byte boundary
relative to the payload start, so readers can wrap the stream zero-copy.
ipc_len records the exact IPC byte length (padding excluded); readers
derive the pad from alignment math alone.