Canvas: build application infrastructure with drag and drop

Change-Id: I5cfd12e67794f3376c5c025af29470d52d77cf16
diff --git a/apps/canvas/src/App.css b/apps/canvas/src/App.css
new file mode 100644
index 0000000..39cbabd
--- /dev/null
+++ b/apps/canvas/src/App.css
@@ -0,0 +1,7 @@
+.react-flow__handle.connectingto {
+  background: #ff6060;
+}
+
+.react-flow__handle.valid {
+  background: #55dd99;
+}
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