[feat] Add Partner Nodes virtual category and rename license filter (#6542)

This PR adds a 'Partner Nodes' virtual category that filters templates
where OpenSource === false, and renames the 'License' filter to 'Runs
on' with values 'ComfyUI' and 'Partner API'. The implementation is
backward compatible and works like the existing 'Basics' category - it
filters templates from any category without duplication. The filter
logic now uses the explicit OpenSource field instead of heuristic
detection. This change coordinates with upcoming workflow_templates repo
updates that will move API templates to GENERATION TYPE categories and
add the OpenSource field to all API node templates.

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-6542-feat-Add-Partner-Nodes-virtual-category-and-rename-license-filter-29f6d73d36508111a85bdf5017f0a100)
by [Unito](https://www.unito.io)

---------

Co-authored-by: Claude <noreply@anthropic.com>

tests-ui/tests/composables/useTemplateFiltering.test.ts

@@ -74,7 +74,8 @@ describe('useTemplateFiltering', () => {
         tags: ['API', 'Video'],
         models: ['Flux'],
         date: '2024-06-01',
-        vram: 15 * 1024 ** 3
+        vram: 15 * 1024 ** 3,
+        openSource: false
       },
       {
         name: 'portrait-flow',