Run pre-commit in CI, too

[armins]

Task

We want to run the same checks in CI as in local dev, see #385

Closes #385

Description

Run precommit (pre-commit and pre-push, latter needs db),
replace existing tests run,
exclude some dirs in precommit

How Has This Been Tested?

in CI

Checklist

• I have successfully run overcommit locally
• I have added tests to cover my changes
• I have linked the issue-id to the task-description
• I have performed a self-review of my own code

[Copilot]

Pull request overview

Aligns CI checks with local Overcommit hooks so CI runs the same pre-commit/pre-push validations described in issue #385.

Changes:

• Switch GitHub Actions CI to run overcommit --run pre-commit and overcommit --run pre-push instead of bespoke Brakeman/RSpec steps.
• Refactor Capybara app construction to reliably return the Rack app, and make the rate-limit feature spec self-contained by setting/restoring env/config inside the spec.
• Expand RuboCop/TrailingWhitespace exclusions to skip .github/, docs/, and images/.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
spec/spec_helper.rb	Refactors Capybara app builder to return the Rack app (not the parse tuple) and exposes it for reuse.
spec/features/rate_limit_feature_spec.rb	Makes CI-only rate limit feature spec configure/restore env + Capybara app within hooks.
.rubocop.yml	Excludes additional non-app directories from RuboCop runs.
.overcommit.yml	Excludes additional directories from the TrailingWhitespace hook.
.github/workflows/ruby.yml	Runs Overcommit pre-commit and pre-push hooks in CI (replacing direct Brakeman/RSpec steps).