feat: RFCP MVP deployed on VPS

Iteration 1:
- Dark theme with 3-way toggle
- Dynamic heatmap gradient (blue→red)
- Radius up to 100km
- Save & Calculate workflow

Iteration 2:
- Terrain overlay toggle
- Batch height operations
- Zoom-dependent heatmap rendering

Infrastructure:
- Backend FastAPI on 8888
- Frontend static build via Caddy
- Systemd services
- Caddy reverse proxy integration

backend/venv/lib/python3.12/site-packages/aiofiles/threadpool/utils.py

@@ -0,0 +1,71 @@
+import functools
+
+
+def delegate_to_executor(*attrs):
+    def cls_builder(cls):
+        for attr_name in attrs:
+            setattr(cls, attr_name, _make_delegate_method(attr_name))
+        return cls
+
+    return cls_builder
+
+
+def proxy_method_directly(*attrs):
+    def cls_builder(cls):
+        for attr_name in attrs:
+            setattr(cls, attr_name, _make_proxy_method(attr_name))
+        return cls
+
+    return cls_builder
+
+
+def proxy_property_directly(*attrs):
+    def cls_builder(cls):
+        for attr_name in attrs:
+            setattr(cls, attr_name, _make_proxy_property(attr_name))
+        return cls
+
+    return cls_builder
+
+
+def cond_delegate_to_executor(*attrs):
+    def cls_builder(cls):
+        for attr_name in attrs:
+            setattr(cls, attr_name, _make_cond_delegate_method(attr_name))
+        return cls
+
+    return cls_builder
+
+
+def _make_delegate_method(attr_name):
+    async def method(self, *args, **kwargs):
+        cb = functools.partial(getattr(self._file, attr_name), *args, **kwargs)
+        return await self._loop.run_in_executor(self._executor, cb)
+
+    return method
+
+
+def _make_proxy_method(attr_name):
+    def method(self, *args, **kwargs):
+        return getattr(self._file, attr_name)(*args, **kwargs)
+
+    return method
+
+
+def _make_proxy_property(attr_name):
+    def proxy_property(self):
+        return getattr(self._file, attr_name)
+
+    return property(proxy_property)
+
+
+def _make_cond_delegate_method(attr_name):
+    """For spooled temp files, delegate only if rolled to file object"""
+
+    async def method(self, *args, **kwargs):
+        if self._file._rolled:
+            cb = functools.partial(getattr(self._file, attr_name), *args, **kwargs)
+            return await self._loop.run_in_executor(self._executor, cb)
+        return getattr(self._file, attr_name)(*args, **kwargs)
+
+    return method