Seedream 4.5 resolution limits: update max dimension and max pixel count to 4704×4704 (from 4096×4096)

### Feature Idea

Hi ComfyUI maintainers,

I noticed a mismatch between the current client-side validation limits for the ByteDance Seedream 4.5 API node and the actual model capabilities.

### Summary

The Seedream 4.5 model should allow up to **4704×4704** output resolution, but the current node-level validation (and/or UI constraints) effectively caps the custom size to **4096×4096** and the maximum total pixel count to **4096×4096**.

### Current behavior

When using the Seedream 4.5 model (e.g. `seedream-4-5-...`), the node rejects or prevents values above 4096 for width/height, and enforces a max pixel count corresponding to 4096×4096.

### Expected behavior

For Seedream 4.5, the node should permit:

* `width <= 4704`
* `height <= 4704`
* `width * height <= 4704 * 4704` (22,127,616 pixels)

Seedream 4.0 should remain unchanged at:

* max dimension 4096
* max pixel count 4096×4096

### Proposed change

Update the Seedream 4.5 validation logic in the ByteDance Seedream node to use:

* `max_dim = 4704` for `seedream-4-5*`
* `max_total_pixels = 4704 * 4704` for `seedream-4-5*`

This keeps Seedream 4.0 limits intact by branching on the selected model.

### Implementation details

File: `comfy_api_nodes/nodes_bytedance.py`
Node: `ByteDanceSeedreamNode`

Suggested approach:

* Keep the UI schema max (width/height) aligned with 4704 to allow entering valid Seedream 4.5 sizes.
* Keep runtime validation model-specific, so Seedream 4.0 remains limited to 4096.

### Backward compatibility

* No behavior change for Seedream 4.0.
* Only relaxes constraints for Seedream 4.5 to match the model’s supported max resolution.

### Evidence / reproducibility

(Please fill one of the following with your concrete evidence)

* Provider documentation link / official spec indicating Seedream 4.5 supports 4704×4704; or
* Successful API response when requesting e.g. 4704×4704; or
* Error returned by API indicating the client-side cap is lower than model capability.

If you’d like, I can open a PR with the exact code change.

Thanks.

### Existing Solutions

_No response_

### Other

_No response_