fix: issue template wording

Author: Felitendo

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -37,3 +37,10 @@ body:
       placeholder: Jellyfin x.y.z, plugin x.y.z, OS ...
     validations:
       required: true
+  - type: checkboxes
+    id: duplicate-check
+    attributes:
+      label: Confirmation
+      options:
+        - label: I have checked that there is no duplicate issue.
+          required: true

.github/ISSUE_TEMPLATE/feature_request.yml

@@ -12,11 +12,6 @@ body:
       placeholder: A clear description of the requested feature.
     validations:
       required: true
-  - type: textarea
-    id: motivation
-    attributes:
-      label: Motivation (optional)
-      description: Why is this useful? This can be a problem, workflow improvement, or other context.
   - type: textarea
     id: proposal
     attributes:
@@ -35,3 +30,10 @@ body:
     attributes:
       label: Additional context
       description: Add extra context, examples, or references here.
+  - type: checkboxes
+    id: duplicate-check
+    attributes:
+      label: Confirmation
+      options:
+        - label: I have checked that there is no duplicate issue.
+          required: true