feat: add remove_issue_reaction, remove_issue_comment_reaction and remove_pull_request_review_comment_reaction tools to the granular issues and pull requests toolsets

[timrogers]

Summary

Adds granular MCP tools for removing reactions from issues or pull requests, issue or pull request comments, and pull request review comments.

Why

The granular toolsets can add reactions but previously had no matching way to remove them, leaving agents unable to undo an accidental or outdated reaction.

What changed

• Added remove_issue_reaction and remove_issue_comment_reaction to the granular issues toolset.
• Added remove_pull_request_review_comment_reaction to the granular pull requests toolset.
• Added destructive annotations, GitHub DELETE endpoint handling, toolset and handler tests, toolsnaps, and generated feature-flag documentation.

MCP impact

• No tool or API changes
• Tool schema or behavior changed
• New tool added

Each new tool mirrors its add-reaction counterpart and accepts the target identifier plus the reaction_id returned when a reaction is created.

Prompts tested (tool changes only)

• "Remove reaction 12345 from issue [docker] build arm64 #42 in owner/repo" — removes an issue or pull request reaction.
• "Remove reaction 67890 from issue comment 999 in owner/repo" — removes an issue or pull request comment reaction.
• "Remove reaction 54321 from pull request review comment 888 in owner/repo" — removes a review-comment reaction.

Security / limits

• No security or limits impact
• Auth / permissions considered
• Data exposure, filtering, or token/size limits considered

The tools retain the same repo scope and granular feature gating as their add counterparts. They are explicitly marked destructive because they delete reactions; GitHub enforces ownership and repository permissions.

Tool renaming

• I am renaming tools as part of this PR (e.g. a part of a consolidation effort)
  • I have added the new tool aliases in deprecated_tool_aliases.go
• I am not renaming tools as part of this PR

Lint & tests

• Linted locally with ./script/lint
• Tested locally with ./script/test

Docs

• Not needed
• Updated (README / docs / examples)

[Copilot]

Copilot review overview

🟡 Changes recommended

All three handlers leak response bodies when GitHub returns API errors.

Get a fresh assessment by requesting another Copilot review.

Review tier: Balanced
Findings: 2

Open (2)

• Close the issue-reaction response on API errors · New
• Close the review-comment response on API errors · New

What changed in this PR

Adds granular MCP tools to remove reactions from issues, comments, and pull request review comments.

Changes:

• Registers three destructive reaction-removal tools.
• Adds DELETE handlers, tests, and schema snapshots.
• Updates generated feature-flag documentation.

File	Description
pkg/​github/​tools.go	Registers the new tools.
pkg/​github/​issues_granular.go	Implements issue and comment removal.
pkg/​github/​pullrequests_granular.go	Implements review-comment removal.
pkg/​github/​helper_test.go	Adds mock DELETE endpoints.
pkg/​github/​granular_tools_test.go	Tests registration and handlers.
pkg/​github/​__toolsnaps__/​remove_issue_reaction.snap	Snapshots issue tool schema.
pkg/​github/​__toolsnaps__/​remove_issue_comment_reaction.snap	Snapshots comment tool schema.
pkg/​github/​__toolsnaps__/​remove_pull_request_review_comment_reaction.snap	Snapshots review-comment schema.
docs/​feature-flags.md	Documents the new tools.

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