Consolidate pull request review tools

[almaleksia]

Consolidating pull request review write tools.

create_and_submit_pull_request_review
create_pending_pull_request_review
submit_pending_pull_request_review
delete_pending_pull_request_review

are consolidated under

pull_request_review_write
with method parameter:
create
submit_pending
delete_pending

CreateAndSubmit and CreatePending merged under create method as they differ only by 2 parameters - event and body.

UPD: validated on curated datasets, no regressions accross models.

[Copilot]

Pull Request Overview

This PR consolidates multiple pull request review tools into a single unified tool. The purpose is to simplify the API by combining separate tools for creating, submitting, and deleting pull request reviews into one tool that uses a method parameter to determine the operation.

• Replaced four separate tools (CreateAndSubmitPullRequestReview, CreatePendingPullRequestReview, SubmitPendingPullRequestReview, DeletePendingPullRequestReview) with one unified PullRequestReviewWrite tool
• Updated tests to use the new consolidated tool with method-based operation selection
• Updated documentation and instructions to reflect the new unified approach

Reviewed Changes

Copilot reviewed 10 out of 11 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
pkg/github/tools.go	Removed old tool registrations and added new unified tool
pkg/github/pullrequests.go	Consolidated multiple tool functions into one with method dispatch
pkg/github/pullrequests_test.go	Updated tests to use new tool name and method parameter
pkg/github/instructions.go	Updated workflow instructions for new tool usage
pkg/github/toolsnaps/*.snap	Updated/removed snapshots for tool definitions
README.md	Updated documentation to reflect consolidated tool

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