Revert "feat: allow users to add their own review style prompts"

[amonkhouse]

Reverts #113

[claude]

Summary

Reverts #113, which let PR authors add personal review-style prompts via review-styles/<login>.md. Removes the review-styles/ files, the personal-style parsing/loading/assembly code in build-review-prompt.ts and its tests, the docs section, and the PR_AUTHOR env from the review workflow.

Issues Found

None. The revert is clean and complete:

• scripts/build-review-prompt.ts, scripts/build-review-prompt.test.ts, and docs/actions.md are byte-identical to their pre-feat: allow users to add their own review style prompts #113 state (git diff 19b759d^ HEAD on these paths is empty).
• Both review-styles/README.md and review-styles/amonkhouse.md are deleted.
• The PR_AUTHOR env block is removed from .github/workflows/claude-review.yml.
• No dangling references remain: grep for review-styles, PersonalStyle, PR_AUTHOR, parsePersonalStyle, assemblePrompt, replace_style, and Reviewer Style across the repo returns nothing.
• The reverted test file imports only buildPrompt, DEFAULT_PROMPT, and loadRepoConfig, all of which the reverted script still exports.

Areas Reviewed

• Testing: build-review-prompt.test.ts still covers default prompt, repo config override, focus areas, and ignore paths. The personal-style tests are removed along with the feature they tested, which is correct.
• Bugs & Edge Cases: No orphaned imports or references left behind.

LGTM.