Add duplicate issue detection as GitHub Action (#41546)

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fix/what does it change/how was it tested (even manually, if necessary)?
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## Summary of the Pull Request
Trying out GitHub models to batch detect duplicate issues.

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## PR Checklist

- [ ] Closes: #xxx
- [ ] **Communication:** I've discussed this with core contributors
already. If the work hasn't been agreed, this work might be rejected
- [ ] **Tests:** Added/updated and all pass
- [ ] **Localization:** All end-user-facing strings can be localized
- [ ] **Dev docs:** Added/updated
- [ ] **New binaries:** Added on the required places
- [ ] [JSON for
signing](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ESRPSigning_core.json)
for new binaries
- [ ] [WXS for
installer](https://github.com/microsoft/PowerToys/blob/main/installer/PowerToysSetup/Product.wxs)
for new binaries and localization folder
- [ ] [YML for CI
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ci/templates/build-powertoys-steps.yml)
for new test projects
- [ ] [YML for signed
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/release.yml)
- [ ] **Documentation updated:** If checked, please file a pull request
on [our docs
repo](https://github.com/MicrosoftDocs/windows-uwp/tree/docs/hub/powertoys)
and link it here: #xxx

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or any additional comments/features here -->
## Detailed Description of the Pull Request / Additional comments

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wherever possible, but list manual validation steps taken as well -->
## Validation Steps Performed

.github/workflows/manual-batch-issue-deduplication.yml

@@ -0,0 +1,20 @@
+name: Manual Batch Issue Deduplication
+
+on:
+  workflow_dispatch: # Only runs when manually triggered
+
+jobs:
+  batch-deduplicate:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Batch Deduplicate Issues
+        uses: pelikhan/action-genai-issue-dedup@v1
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          label-duplicate: "potential duplicate"
+          comment-duplicate: true
+          close-duplicate: false
+          batch-size: 100 
+          since: '2019-05-05T00:00:00Z' # Process issues dating back to 2019
+          duplicate-comment-template: "This issue appears to be a duplicate of #{duplicate_issue_number}."
+          # Add other action-specific inputs if needed