fix: Skip docs verification for closed pull requests (#522)

## Summary
- Skip root Functions index artifact verification for closed
pull-request runs.
- Preserve verification for active pull requests, pushes, schedules, and
manual runs.

## Root cause
Closed pull-request events intentionally skip Build-Docs, so no docs
artifact exists for the unconditional verifier to download.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Author: MariusStorhaug

.github/workflows/Workflow-Test-Default.yml

@@ -64,6 +64,7 @@ jobs:
         ^\.github/workflows/(?!Release\.yml$|Linter\.yml$)
 
   VerifyRootFunctionsIndexDefault:
+    if: github.event.action != 'closed'
     name: Verify root Functions index [Default]
     runs-on: ubuntu-latest
     needs:

.github/workflows/Workflow-Test-WithManifest.yml

@@ -64,6 +64,7 @@ jobs:
         ^\.github/workflows/(?!Release\.yml$|Linter\.yml$)
 
   VerifyRootFunctionsIndexWithManifest:
+    if: github.event.action != 'closed'
     name: Verify root Functions index [WithManifest]
     runs-on: ubuntu-latest
     needs: