test(skills): pin the home-hermes discovery source record

Ported from the duplicate PR #15732: asserts the source id, owner and exists flag that skill-agent-filter joins against.

src/main/skills/discovery.test.ts

@@ -503,6 +503,10 @@ describe('skill discovery', () => {
         })
       ])
     )
+    expect(result.sources.find((source) => source.id === 'home-hermes')).toMatchObject({
+      owner: 'hermes',
+      exists: true
+    })
   })
 
   it('discovers worktree .agents skill symlinks from the requested cwd', async () => {