fix: add missing pagination on get_reviews

[RossTarrant]

Summary

Add pagination support to get_reviews method in pull_request_read tool, bringing it in line with other paginated methods like get_files, get_comments, and get_check_runs.

Why

Fixes #2347 - GetPullRequestReviews passed nil options to ListReviews, silently truncating results to the first page (~30 items) with no pagination support.

What changed

• Added PaginationParams to GetPullRequestReviews function signature
• Forward Page/PerPage to ListReviews API call
• Updated tool description to document pagination support
• Added pagination test case and updated failure test to verify default query params

MCP impact

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

Prompts tested (tool changes only)

• get_reviews with page and perPage parameters on a PR with 37 reviews - confirmed pagination params are forwarded correctly
• get_reviews without pagination params - confirmed defaults (page=1, per_page=30) are sent

Example Prompts:

Basic fetch (default pagination): List the reviews on PR ID: 1 in rosstarrant/octopus-mcp
Explicit pagination - first page: Get the first 10 reviews on rosstarrant/octopus-mcp PR ID: 1
Explicit pagination - second page: Get page 2 of reviews on rosstarrant/octopus-mcp PR ID: 1, with 10 per page
Edge case - page beyond results: Get page 100 of reviews on rosstarrant/octopus-mcp PR ID: 1

Security / limits

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

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

Note: if you're renaming tools, you must add the tool aliases. For more information on how to do so, please refer to the official docs.

Lint & tests

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

Docs

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

[Copilot]

Pull request overview

Adds REST pagination support to the get_reviews method of the pull_request_read MCP tool so callers can fetch review pages beyond GitHub’s default first page.

Changes:

• Extend GetPullRequestReviews to accept PaginationParams and pass Page/PerPage into PullRequests.ListReviews.
• Add/adjust unit tests to assert pagination query params are forwarded (including default page=1&per_page=30).
• Update tool/docs text (toolsnap + README) to document pagination support for get_reviews.

Show a summary per file

File	Description
pkg/github/pullrequests.go	Wires PaginationParams into ListReviews and updates tool method description text.
pkg/github/pullrequests_test.go	Adds a paginated success case and asserts default pagination query params on failure path.
pkg/github/toolsnaps/pull_request_read.snap	Updates the tool schema snapshot description to mention pagination for get_reviews.
README.md	Mirrors the updated get_reviews pagination note in generated docs.

Copilot's findings

• Files reviewed: 4/4 changed files
• Comments generated: 2