feat: add commit comment tools

Adds five commit-comment tools, bringing the total to 47. They follow the existing core → tools → registry pattern and are wired through the AI SDK entry, presets, the @github-tools/sdk/eve subpath, the chat app, and docs.

createCommitComment can be general or anchored to a diff line via path + position. The three write tools require approval by default.

Presets: reads are in code-review, repo-explorer, and maintainer; createCommitComment is also in code-review; update/delete are maintainer-only — mirroring how PR and gist comment tools are distributed.

Example

import { createGithubTools } from '@github-tools/sdk'
import { generateText } from 'ai'

const result = await generateText({
  model: yourModel,
  tools: createGithubTools({ token: process.env.GITHUB_TOKEN! }),
  prompt: 'Leave a comment on commit abc123 in vercel/ai noting the missing null check, then list all comments on it.',
})

Or cherry-pick a single factory:

import { createCommitComment } from '@github-tools/sdk'

const tools = {
  createCommitComment: createCommitComment(process.env.GITHUB_TOKEN!),
}