docs: require focused PRs (one feature or fix)

.github/PULL_REQUEST_TEMPLATE.md

@@ -27,6 +27,7 @@ Fixes #
 
 ## Checklist
 
+- [ ] PR is focused on one feature or one fix (no unrelated changes)
 - [ ] Branch rebased onto `dev` (`git rebase origin/dev`)
 - [ ] `./gradlew ktlintCheck` passes (ran `ktlintFormat` first)
 - [ ] `./gradlew testDebugUnitTest` green (or CI unit-tests job)

CONTRIBUTING.md

@@ -22,6 +22,8 @@ If an open PR already covers it, review or improve that one instead of opening a
 
 Every change must go through a pull request (PR) targeting the `dev` staging branch. Do not push directly to `main` or `dev`.
 
+**Keep PRs focused: one feature or one fix per PR.** Unrelated changes belong in separate PRs so each one stays easy to review, test, and revert.
+
 1. **Pick or open an issue** to discuss the changes you want to make.
 2. **Create a branch** off `dev` using the following naming convention:
    - Features: `feat/short-description` (optionally `feat/issue-N-description`)
@@ -124,6 +126,7 @@ We enforce Kotlin coding conventions and Jetpack Compose best practices.
 Before submitting your PR, please verify:
 
 - [ ] I searched open/closed PRs + issues for duplicates (see *Before You Start*).
+- [ ] PR is focused on one feature or one fix (no unrelated changes).
 - [ ] Branch is rebased onto current `dev` (`git rebase origin/dev`).
 - [ ] `./gradlew ktlintCheck` passes (ran `ktlintFormat` first — no hand edits).
 - [ ] `checkColorLiterals` passes (no hardcoded Color literals outside theme/).