feat(workflow): Enable keyboard delete for all node types including Start

Removes explicit Start node exclusion from handleNodesDelete function:
- Remove BlockEnum.Start filter from bundled nodes selection
- Remove BlockEnum.Start filter from selected node detection
- Allows DEL/Backspace keys to delete Start nodes same as other nodes
- Button delete already worked, now keyboard delete works too

Fixes: Start nodes can now be deleted via both button and keyboard shortcuts

🤖 Generated with [Claude Code](https://claude.ai/code)

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

web/app/components/workflow/hooks/use-nodes-interactions.ts

@@ -1656,7 +1656,7 @@ export const useNodesInteractions = () => {
 
     const nodes = getNodes()
     const bundledNodes = nodes.filter(
-      node => node.data._isBundled && node.data.type !== BlockEnum.Start,
+      node => node.data._isBundled,
     )
 
     if (bundledNodes.length) {
@@ -1669,7 +1669,7 @@ export const useNodesInteractions = () => {
     if (edgeSelected) return
 
     const selectedNode = nodes.find(
-      node => node.data.selected && node.data.type !== BlockEnum.Start,
+      node => node.data.selected,
     )
 
     if (selectedNode) handleNodeDelete(selectedNode.id)