docs: add GitHub PR template (#227)

Adds a .github/PULL_REQUEST_TEMPLATE.md with sections for summary,
type of change, screenshots, testing steps, and project-specific
checklist items (HermesScaffold, NavigationController, room schema,
screen dedup check).

Co-authored-by: M57 <hy4ri@users.noreply.github.com>

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,68 @@
+## Summary
+
+<!-- One-sentence summary of what this PR does. -->
+
+Fixes #<!-- issue number -->
+
+## Type of change
+
+<!-- Check the type that applies. Delete the rest. -->
+
+- [ ] 🐛 Bug fix
+- [ ] ✨ Feature
+- [ ] 🎨 UX improvement
+- [ ] ♻️ Refactor
+- [ ] 🔧 CI / build config
+- [ ] 📝 Documentation
+- [ ] 🔒 Security
+
+## Screenshots / screen recordings
+
+<!-- Required for UI changes. Drag & drop images or link to recordings. -->
+
+_Before:_
+
+_After:_
+
+## What changed
+
+<!--
+  Describe the changes in detail — what was wrong, what was done to fix it,
+  key decisions made, trade-offs considered. For UI changes, explain the
+  reasoning behind layout, color, or interaction decisions.
+-->
+
+## How to test
+
+<!--
+  Steps to verify the change works correctly. Example:
+
+  1. Open the app
+  2. Navigate to …
+  3. Tap …
+  4. Verify that …
+-->
+
+## Checklist
+
+- [ ] Code follows the project's style (ktlint passes)
+- [ ] No new compiler warnings introduced
+- [ ] If adding a new screen, checked that existing screens don't already cover the functionality (see `NavigationKeys.kt`/`ls ui/`)
+- [ ] Routes all navigation through `NavigationController.navigateTo()` — no raw `backStack.add()` from UI callbacks
+- [ ] Uses `HermesScaffold` instead of raw `Scaffold` for new/rewritten screens
+- [ ] Room schema directory updated if entities changed
+- [ ] Tested the change on a real device or CI APK
+- [ ] CI is green (all checks pass: ktlint, Android Lint, unit tests, build)
+
+## Related issues
+
+<!--
+  Link any related issues, PRs, or discussions.
+  e.g., Closes #N, Refs #M, Related to #P
+-->
+
+## Notes for reviewers
+
+<!--
+  Any gotchas, follow-up work, or things to watch out for.
+-->