Add Qualified Bug Report issue template

.github/ISSUE_TEMPLATE/qualified-bug.yml

@@ -0,0 +1,24 @@
+name: Qualified Bug Report
+description: "[Developers] For qualified bug reports only. (Use Discussions if unsure.)"
+labels: ["bug"]
+body:
+  - type: checkboxes
+    attributes:
+      label: Problem scope
+      description: Use Discussions if you're unsure which component (DAVx⁵, calendar app, server, …) causes your problem.
+      options:
+        - label: I'm sure that this is a DAVx⁵ problem.
+          required: true
+  - type: checkboxes
+    attributes:
+      label: App version
+      options:
+        - label: I'm using the latest available DAVx⁵ version.
+          required: true
+  - type: textarea
+    label: Summary
+    description: A short summary of the problem.
+    placeholder: SomeException during sync under this specific condition
+    validations:
+      required: true
+