feat(svelte): add SvelteFlowProvider and useSvelteFlow hook

packages/svelte/src/routes/usesvelteflow/Flow.svelte

@@ -0,0 +1,65 @@
+<script lang="ts">
+  import SvelteFlow, {
+    Controls,
+    Background,
+    BackgroundVariant,
+    Minimap,
+    Panel,
+    createNodes,
+    createEdges,
+    useSvelteFlow
+  } from '../../lib/index';
+ 
+  const nodes = createNodes([
+    {
+      id: '1',
+      type: 'input',
+      data: { label: 'Input Node' },
+      position: { x: 150, y: 5 }
+    },
+    {
+      id: '2',
+      type: 'default',
+      data: { label: 'Node' },
+      position: { x: 0, y: 150 }
+    },
+    {
+      id: '3',
+      type: 'output',
+      data: { label: 'Output Node' },
+      position: { x: 300, y: 150 }
+    }
+  ]);
+
+  const edges = createEdges([
+    {
+      id: '1-2',
+      type: 'default',
+      source: '1',
+      target: '2',
+      label: 'Edge Text'
+    },
+    {
+      id: '1-3',
+      type: 'smoothstep',
+      source: '1',
+      target: '3'
+    }
+  ]);
+
+  const svelteFlow = useSvelteFlow();
+</script>
+
+<SvelteFlow
+  {nodes}
+  {edges}
+>
+  <Controls />
+  <Background variant={BackgroundVariant.Dots} />
+  <Minimap />
+  <Panel position="top-right">
+    <button on:click={() => svelteFlow.zoomIn()}>zoom in</button>
+    <button on:click={() => svelteFlow.zoomOut({ duration: 1000 })}>zoom out transition</button>
+    <button on:click={() => svelteFlow.fitView()}>fitView</button>
+  </Panel>
+</SvelteFlow>