ci: allow skipping E2E tests with 2 approvals for dependency-only PRs

[ben-dz]

Problem

Release PRs that only bump versions in Cargo.lock, Cargo.toml, and CHANGELOG.md still require the full E2E suite to pass. These tests are slow and resource-intensive, and they add no value when the diff contains zero behavioral changes — making releases take longer than necessary.

Proposal

Add a mechanism to skip E2E tests when both conditions are met:

1. The PR only modifies Cargo.lock, Cargo.toml (any path), and/or CHANGELOG.md
2. The PR has at least 2 approving reviews

Implementation options

• GitHub Actions path filter + branch protection: Use paths / paths-ignore filters on the E2E workflow so it doesn't trigger for dependency-only file sets. Combine with a required status check that is satisfied either by E2E passing or by a lightweight "skip" job that runs when the path filter excludes E2E.
• Label-based override: A skip-e2e label that a maintainer can apply after verifying the diff is dependency-only. The workflow checks for the label and short-circuits. Branch protection still requires 2 approvals.
• Merge queue rule: If using merge queues, configure a separate queue rule for dependency-only PRs that omits the E2E check.

Acceptance criteria

• E2E tests are not required to merge a PR that only changes Cargo.lock, Cargo.toml, and/or CHANGELOG.md
• At least 2 approving reviews are still required before merge
• PRs that touch any other files still require E2E to pass