chore: add migration check job to CI workflow

[Anty0]

Summary

• Adds a new migration-check CI job that runs ./gradlew diffChangeLog and fails if migration files are out of date
• Reuses the backend build artifact (same as schema-check and backend-test)
• Wired into everything-passed gate so PRs with stale migrations cannot merge

Summary by CodeRabbit

• Chores

  • CI pipeline now includes an automated migration check that validates database migration files are up-to-date before completing builds.

• Refactor

  • Database indexing was adjusted to change how certain activity records are indexed, improving query behavior and performance in relevant lookups.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

---

📝 Walkthrough

Walkthrough

Adds a CI "Migration Check" job to .github/workflows/test.yml to validate database migration diffs post-build, and modifies ActivityModifiedEntity to replace a single-column branch_id index with a composite index on (activity_revision_id, branch_id).

Changes

Cohort / File(s)	Summary
CI Workflow Migration Validation .github/workflows/test.yml	Adds a new "Migration Check 🗃️" job that runs after backend-build, downloads the backend build, runs ./gradlew diffChangeLog, fails if migration diffs are present, and integrates the job into the workflow's needs graph (including the final "Everything passed" aggregation).
Database index change backend/data/src/main/kotlin/io/tolgee/model/activity/ActivityModifiedEntity.kt	Replaces existing single-column index on branch_id with a composite index on (activity_revision_id, branch_id) for ActivityModifiedEntity (index definition changed; no API signature changes).

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Suggested reviewers

• bdshadow

Poem

🐰 I hop through CI and schema lines,

Gradle hums while migration signs,
Composite indexes align the trail,
Workflow checks ensure we prevail,
A tiny rabbit cheers—no fail!

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: adding a migration check job to the CI workflow, which is the primary objective of this pull request.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch jirikuchynka/migration-check-ci

---

_{Comment @coderabbitai help to get the list of available commands and usage tips.}