Fix/pre commit on fork prs

[cristian-tamblay]

Summary

Two CI changes.

Pre-commit checks only listened to push, which covers branches that live in this repository but not pull requests from forks. PR #828 came from a fork,
so the hooks never ran on it and its lint errors surfaced on develop after the merge instead of on the PR (fixed in b3b7296). Adding pull_request
closes that gap.

The Code Review workflow is removed. It ran an on-demand Claude review triggered by a /review comment, and it has not completed a review since the day
it was set up.

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Type of Change

Check all that apply like this [x]:

• Backend change
• Frontend change
• CI / Workflow change
• Build / Packaging change
• Bug fix
• Documentation

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Changes (by file)

• .github/workflows/pre-commit.yaml: add the pull_request trigger next to push, so the hooks also run on pull requests opened from forks. Internal
  branches keep firing once, GitHub deduplicates the two events. A comment records why, since the reason is not visible from the file itself.
• .github/workflows/code-review.yaml: deleted.

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Testing

This PR is its own check for the first change: the pre-commit check should appear in its list, which is what PR #828 was missing. That only proves the
workflow still runs on an internal branch, since this branch lives in the repository. The real verification is the next pull request opened from a fork.

For reference, the check lists as they stood:

PR #838 (internal branch): alembic translations pre-commit pytest react-build
PR #828 (fork): alembic translations pytest react-build

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Notes

Run history for the removed workflow, 55 runs in total:

42 skipped 8 success 4 failure 1 startup_failure

The 8 successful runs are all from 2026-04-16, the day the workflow was added and iterated on. It has not produced a review since. The 42 skipped runs come
from the trigger being a bare issue_comment, so every comment on any issue or pull request starts a runner that evaluates the if, finds no /review
and stops.

The ANTHROPIC_API_KEY repository secret is now unused, since this was the only workflow that read it. Revoking it is a separate step in Settings and is
not part of this PR.