Bug and PR Template enhancements (#13297)

* Add nightly build reproducibility checkbox

Add a required checkbox to the bug report template prompting reporters to verify the issue is reproducible in the latest nightly build (links to the nightly builds release). This helps catch issues already fixed in nightly releases and reduces duplicate reports.

* Add PR artifact download guide to template

Update the pull request template to include a commented section and a link to the OrcaSlicer wiki explaining how to download artifacts from a PR. This helps contributors and reviewers locate and retrieve build/test artifacts for verification and testing.

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -11,6 +11,13 @@ body:
         For this, please use the [Feature request](https://github.com/OrcaSlicer/OrcaSlicer/issues/new?assignees=&labels=&projects=&template=feature_request.yml) issue type or you can discuss your idea on our [Discord server](https://discord.gg/P4VE9UY9gJ) with others.
         
         Before filing, please check if the issue already exists (either open or closed) by using the search bar on the issues page. If it does, comment there. Even if it's closed, we can reopen it based on your comment.
+  - type: checkboxes
+    attributes:
+      label: Is this issue reproducible in the latest nightly build?
+      description: Please verify this issue still happens in the latest nightly build first. It may already be fixed there: [Nightly builds](https://github.com/OrcaSlicer/OrcaSlicer/releases/tag/nightly-builds).
+      options:
+        - label: I have checked the latest nightly build and the issue is still reproducible
+          required: true
   - type: checkboxes
     attributes:
       label: Is there an existing issue for this problem?

.github/pull_request_template.md

@@ -19,3 +19,9 @@
 <!--
 > Please describe the tests that you have conducted to verify the changes made in this PR.
 -->
+
+<!--
+> A guide for users on how to download the artifacts from this PR.
+-->
+
+[How to Download Pull Requests Artifacts for Testing](https://www.orcaslicer.com/wiki/how_to_download_pr_artifacts)