feat: gate server routes + preview + register ImageGate

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

gates/gate_server.py

@@ -0,0 +1,44 @@
+# gates/gate_server.py
+import base64
+import io
+
+import numpy as np
+from aiohttp import web
+from PIL import Image
+from server import PromptServer
+
+from .gate_bus import GateBus
+
+routes = PromptServer.instance.routes
+
+
+def send_preview(node_id, image, n_routes):
+    arr = (image[0].cpu().numpy() * 255.0).clip(0, 255).astype("uint8")
+    buf = io.BytesIO()
+    Image.fromarray(arr).save(buf, "PNG")
+    b64 = base64.b64encode(buf.getvalue()).decode()
+    PromptServer.instance.send_sync(
+        "datasete-gate-show",
+        {"id": str(node_id), "image": b64, "routes": int(n_routes)},
+    )
+
+
+@routes.post("/datasete_gate/choice")
+async def _choice(request):
+    post = await request.post()
+    GateBus.put(post.get("id"), post.get("message"))
+    return web.json_response({})
+
+
+@routes.post("/datasete_gate/mask")
+async def _mask(request):
+    reader = await request.multipart()
+    node_id, data = None, None
+    async for part in reader:
+        if part.name == "id":
+            node_id = await part.text()
+        elif part.name == "mask":
+            data = await part.read(decode=False)
+    if node_id is not None:
+        GateBus.put_mask(node_id, data)
+    return web.json_response({})