Add feature_request.md

Author: ashtanko

.github/ISSUE_TEMPLATE/feature_request.md

@@ -0,0 +1,19 @@
+---
+name: 💡 Feature Request
+about: Suggest a new Flutter feature or improvement
+title: "[Feature] <short description>"
+labels: enhancement
+assignees: ''
+---
+
+### Feature description
+Describe what you’d like to see added or improved.
+
+### Motivation
+Why is this feature important or useful?
+
+### Alternatives
+Are there any existing workarounds or alternatives?
+
+### Additional context
+Add any context or mockups to support your request.