feat: add category support for blueprints and protect global blueprints (#8378)

## Summary

This PR adds two related features for subgraph blueprints:

### 1. Protect Global Blueprints from Deletion
- Added `isGlobalBlueprint()` helper that distinguishes blueprints by
`python_module` field
- User blueprints have `python_module: 'blueprint'`
- Global (installed) blueprints have `python_module` set to the node
pack name
- Guarded `deleteBlueprint()` to show a warning toast for global
blueprints
- Hidden delete menu in node library for global blueprints

### 2. Category Support for Blueprints
- User blueprints now use category `Subgraph Blueprints/User`
- Global blueprints use `Subgraph Blueprints/{category}` if category is
provided, otherwise `Subgraph Blueprints`
- Extended `GlobalSubgraphData.info` type with optional `category` field
- Added `category` to `zSubgraphDefinition` schema

## Files Changed
- `src/stores/subgraphStore.ts` - Core logic for both features
- `src/stores/subgraphStore.test.ts` - Tests for `isGlobalBlueprint`
- `src/components/sidebar/tabs/nodeLibrary/NodeTreeLeaf.vue` - Hide
delete menu for global blueprints
- `src/scripts/api.ts` - Extended `GlobalSubgraphData` type
- `src/platform/workflow/validation/schemas/workflowSchema.ts` - Added
category to schema
- `src/locales/en/main.json` - Added translation key

## Testing
- ✅ `pnpm typecheck` passed
- ✅ `pnpm lint` passed

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-8378-feat-add-category-support-for-blueprints-and-protect-global-blueprints-2f66d73d36508137aa67c2d88c358b69)
by [Unito](https://www.unito.io)

---------

Co-authored-by: Subagent 5 <subagent@example.com>
Co-authored-by: Amp <amp@ampcode.com>
Co-authored-by: GitHub Action <action@github.com>
Co-authored-by: AustinMroz <austin@comfy.org>

src/platform/workflow/validation/schemas/workflowSchema.ts

@@ -394,6 +394,7 @@ interface SubgraphDefinitionBase<
   id: string
   revision: number
   name: string
+  category?: string
 
   inputNode: T extends ComfyWorkflow1BaseInput
     ? z.input<typeof zExportedSubgraphIONode>
@@ -425,6 +426,7 @@ const zSubgraphDefinition = zComfyWorkflow1
     id: z.string().uuid(),
     revision: z.number(),
     name: z.string(),
+    category: z.string().optional(),
     inputNode: zExportedSubgraphIONode,
     outputNode: zExportedSubgraphIONode,