chore: streamline issue templates, redirect GitHub issues to Gitea

Simplify bug report (5 fields → 3 + search checkbox) and feature
request (4 fields → 2). Add GitHub ISSUE_TEMPLATE config that
disables blank issues and redirects to Gitea.

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,8 @@
+blank_issues_enabled: false
+contact_links:
+  - name: Report a Bug
+    url: https://gitea.lerkolabs.com/lerkolabs/uptop/issues/new?template=bug_report.yaml
+    about: Report bugs on our Gitea instance
+  - name: Request a Feature
+    url: https://gitea.lerkolabs.com/lerkolabs/uptop/issues/new?template=feature_request.yaml
+    about: Suggest features on our Gitea instance