feat(styles): one stylesheet source for react and svelte (#3350)

* feat(styles): create stylesheets for react and svelte based on one source

* refactor(styling): cleanup

* refactor(postcss): share a config

* refactor(postcss): replace env hack with env file

packages/svelte/src/routes/overview/+page.svelte

@@ -12,8 +12,10 @@
     type EdgeTypes
   } from '../../lib/index';
 
-  import { CustomNode } from './CustomNode';
-  import { CustomEdge } from './CustomEdge';
+  import CustomNode from './CustomNode.svelte';
+  import CustomEdge from './CustomEdge.svelte';
+
+  import '../../styles/style.css';
 
   const nodeTypes: NodeTypes = {
     custom: CustomNode

packages/svelte/src/routes/overview/CustomEdge.svelte

@@ -5,7 +5,7 @@
     useSvelteFlow,
     type EdgeProps,
     getBezierPath
-  } from '../../../lib/index';
+  } from '../../lib/index';
 
   type $$Props = EdgeProps;
 

packages/svelte/src/routes/overview/CustomEdge/index.ts

@@ -1 +0,0 @@
-export { default as CustomEdge } from './Custom.svelte';

packages/svelte/src/routes/overview/CustomNode.svelte

@@ -1,5 +1,5 @@
 <script lang="ts">
-  import { Handle, Position, type NodeProps } from '../../../lib/index';
+  import { Handle, Position, type NodeProps } from '../../lib/index';
 
   type $$Props = NodeProps;
 

packages/svelte/src/routes/overview/CustomNode/index.ts

@@ -1 +0,0 @@
-export { default as CustomNode } from './Custom.svelte';