feat: Add feature request issue template

Standardized feature request template with:
- Problem description section
- Detailed solution proposal
- Alternative solutions
- Use cases and acceptance criteria
- Checkboxes for tracking
- Part of TIER 5: Advanced Features (Task 10)

Author: rigoryanych

.github/ISSUE_TEMPLATE/feature_request.md

@@ -0,0 +1,28 @@
+---
+name: Feature request
+about: Suggest an idea for this project
+title: '[FEATURE] '
+labels: 'enhancement'
+assignees: ''
+
+---
+
+## Description
+Is your feature request related to a problem? Please describe.
+
+## Solution
+Describe the solution you'd like. Be as detailed as possible.
+
+## Alternative Solutions
+Describe any alternative solutions or features you've considered.
+
+## Use Cases
+Describe use cases where this feature would be helpful.
+
+## Acceptance Criteria
+- [ ] Criterion 1
+- [ ] Criterion 2
+- [ ] Criterion 3
+
+## Additional Context
+Add any other context, mockups, or examples here.