feat: Add search_aliases field to node schema

Adds `search_aliases` field to improve node discoverability. Users can define alternative search terms for nodes (e.g., "text concat" → StringConcatenate).

Changes:
- Add `search_aliases: list[str]` to V3 Schema
- Add `SEARCH_ALIASES` support for V1 nodes
- Include field in `/object_info` response
- Add aliases to high-priority core nodes

V1 usage:
```python
class MyNode:
    SEARCH_ALIASES = ["alt name", "synonym"]
```

V3 usage:
```python
io.Schema(
    node_id="MyNode",
    search_aliases=["alt name", "synonym"],
    ...
)
```

## Related PRs
- Frontend: Comfy-Org/ComfyUI_frontend#XXXX (draft - merge after this)
- Docs: Comfy-Org/docs#XXXX (draft - merge after stable)

comfy_extras/nodes_post_processing.py

@@ -550,6 +550,7 @@ class BatchImagesNode(io.ComfyNode):
             node_id="BatchImagesNode",
             display_name="Batch Images",
             category="image",
+            search_aliases=["batch", "image batch", "batch images", "combine images", "merge images", "stack images"],
             inputs=[
                 io.Autogrow.Input("images", template=autogrow_template)
             ],