Add ready_for_review trigger to code review workflow

[nickwinder]

Why

The workflow was missing the `ready_for_review` trigger, meaning it would not fire when a draft PR was converted to ready for review.

In practice this appeared to work — but only by accident. With GitHub Copilot's automatic reviewer ruleset enabled, Copilot auto-assigns itself as a reviewer when a PR becomes ready. That auto-assignment fires a `review_requested` event, which was in the trigger list, causing the workflow to run indirectly.

This created a hidden dependency on Copilot being installed and configured. Without it (or if the ruleset changes), the workflow would silently stop triggering for draft PRs being promoted to ready.

`review_requested` is also removed for the same reason — it was only serving as the accidental workaround. Re-triggering via `@mention` is already handled by the `issue_comment` trigger.

References:

• What event fires when converting a draft PR to ready? · GitHub community #23427
• pull_request default activity types should include ready_for_review · GitHub community #139644

Summary

• Add `ready_for_review` to `pull_request` event types in the workflow so the trigger fires directly when a draft PR is promoted
• Remove `review_requested`, which was an accidental workaround via Copilot's auto-reviewer ruleset and is no longer needed
• Map `ready_for_review` to the `open` trigger type in `action.yml` — it was missing from the `case` statement, causing the action to see trigger type `unknown` and skip the review entirely

[github-actions]

📋 PR Summary:
This PR adds the ready_for_review trigger type to handle draft PRs being promoted to ready status, replacing the review_requested trigger which was only working accidentally due to GitHub Copilot's auto-reviewer ruleset. The change ensures the workflow fires directly when a draft PR becomes ready, without depending on external tooling.

2 files reviewed

File	Changes
.github/workflows/code-review.yml	Replace review_requested with ready_for_review trigger type
action.yml	Map ready_for_review to 'open' trigger type in case statement

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No issues found. Changes look good.