Change description field to textarea in Add New Feature modal

The description field in the Add New Feature modal is now a textarea instead of
an input, allowing users to enter multi-line feature descriptions more easily.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

test-results/.last-run.json

@@ -0,0 +1,4 @@
+{
+  "status": "failed",
+  "failedTests": []
+}