dev: Added contributor guidelines and updated the PR template

.github/PULL_REQUEST_TEMPLATE.yml

@@ -0,0 +1,47 @@
+name: Pull Request
+description: Submit a contribution to ElegantFin
+title: "[PR] <Short title for your changes>"
+labels: []
+assignees: []
+
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Please follow our [Contributor Guidelines](../CONTRIBUTING.md) and keep your PR focused on a single improvement or fix.
+  - type: textarea
+    id: description
+    attributes:
+      label: Description
+      description: Describe your changes and the reason behind them.
+      placeholder: What did you change and why?
+    validations:
+      required: true
+  - type: textarea
+    id: screenshots
+    attributes:
+      label: Screenshots
+      description: Add before/after images of any visual changes.
+      placeholder: Drag and drop or paste images here.
+    validations:
+      required: false
+  - type: textarea
+    id: testing
+    attributes:
+      label: Cross-platform Testing
+      description: Describe how you verified this works across devices (e.g., desktop, mobile, TV).
+    validations:
+      required: true
+  - type: checkboxes
+    id: checklist
+    attributes:
+      label: Checklist
+      options:
+        - label: I followed the style conventions (`em` units, minimal media queries).
+          required: true
+        - label: I avoided unnecessary use of `!important`.
+          required: true
+        - label: I commented my code where applicable.
+          required: true
+        - label: I tested my changes across viewports.
+          required: true