Fix failing "Request Copilot review" CI job

[Copilot]

The copilot-review job was unconditionally failing because gh api exits non-zero on any API error. The runner was granting only PullRequests: read despite the job declaring permissions: pull-requests: write — a known behaviour when repo/org enforces read-only GITHUB_TOKEN defaults. This caused a 403 to bubble up as a job failure.

Changes

• .github/workflows/ci.yml — append || echo "::warning::..." to the gh api call so the step exits cleanly on permission errors while still emitting a visible workflow annotation. Aligns the step behaviour with the continue-on-error: true already on the job.

- -f "reviewers[]=copilot-pull-request-reviewer"
+ -f "reviewers[]=copilot-pull-request-reviewer" \
+ || echo "::warning::Could not request Copilot review (the token may lack pull-requests: write access, or Copilot PR reviews may not be enabled for this repository)"