feat(github): add pull request creation service

- Create GitHubPRService for PR creation
- Add POST /api/github/pr endpoint
- Auto-add AI Development Cockpit attribution
- Commit multiple files to new branch
- TDD with 1 passing test

Part of Phase 2 - GitHub Integration
COMPLETES GITHUB INTEGRATION!

Author: ScientiaCapital

src/app/api/github/pr/route.ts

@@ -0,0 +1,59 @@
+import { createClient } from '@/lib/supabase/server'
+import { GitHubPRService } from '@/services/github/pr.service'
+import { NextRequest, NextResponse } from 'next/server'
+import { cookies } from 'next/headers'
+
+export async function POST(request: NextRequest) {
+  try {
+    const cookieStore = cookies()
+    const supabase = createClient(cookieStore)
+
+    // Get current user session
+    const { data: { session }, error: sessionError } = await supabase.auth.getSession()
+
+    if (sessionError || !session) {
+      return NextResponse.json({ error: 'Not authenticated' }, { status: 401 })
+    }
+
+    const githubToken = session.provider_token
+    if (!githubToken) {
+      return NextResponse.json({ error: 'No GitHub token found' }, { status: 401 })
+    }
+
+    const body = await request.json()
+    const { owner, repo, branchName, baseBranch, title, prBody, files } = body
+
+    // Validation
+    if (!owner || !repo || !branchName || !baseBranch || !title || !files) {
+      return NextResponse.json(
+        { error: 'Missing required fields' },
+        { status: 400 }
+      )
+    }
+
+    const prService = new GitHubPRService(githubToken)
+    const result = await prService.createPullRequest({
+      owner,
+      repo,
+      branchName,
+      baseBranch,
+      title,
+      body: prBody,
+      files
+    })
+
+    return NextResponse.json({
+      success: true,
+      ...result
+    })
+  } catch (error) {
+    console.error('PR creation error:', error)
+    return NextResponse.json(
+      {
+        success: false,
+        error: error instanceof Error ? error.message : 'PR creation failed'
+      },
+      { status: 500 }
+    )
+  }
+}

src/services/github/pr.service.ts

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+import { Octokit } from '@octokit/rest'
+
+export interface PRFile {
+  path: string
+  content: string
+}
+
+export interface CreatePROptions {
+  owner: string
+  repo: string
+  branchName: string
+  baseBranch: string
+  title: string
+  body: string
+  files: PRFile[]
+}
+
+export interface PRResult {
+  url: string
+  number: number
+}
+
+export class GitHubPRService {
+  private octokit: Octokit
+
+  constructor(accessToken: string) {
+    this.octokit = new Octokit({ auth: accessToken })
+  }
+
+  async createPullRequest(options: CreatePROptions): Promise<PRResult> {
+    const { owner, repo, branchName, baseBranch, title, body, files } = options
+
+    console.log(`🔄 Creating PR: ${owner}/${repo} (${branchName} → ${baseBranch})`)
+
+    // Step 1: Get base branch SHA
+    const { data: baseBranchData } = await this.octokit.repos.getBranch({
+      owner,
+      repo,
+      branch: baseBranch
+    })
+
+    const baseSha = baseBranchData.commit.sha
+
+    // Step 2: Create new branch
+    await this.octokit.git.createRef({
+      owner,
+      repo,
+      ref: `refs/heads/${branchName}`,
+      sha: baseSha
+    })
+
+    console.log(`✅ Created branch: ${branchName}`)
+
+    // Step 3: Commit files to new branch
+    for (const file of files) {
+      await this.octokit.repos.createOrUpdateFileContents({
+        owner,
+        repo,
+        path: file.path,
+        message: `Add ${file.path}`,
+        content: Buffer.from(file.content).toString('base64'),
+        branch: branchName
+      })
+    }
+
+    console.log(`✅ Committed ${files.length} files`)
+
+    // Step 4: Create pull request
+    const { data: pr } = await this.octokit.pulls.create({
+      owner,
+      repo,
+      title,
+      body: `${body}\n\n---\n🤖 Generated with [AI Development Cockpit](https://github.com/ScientiaCapital/ai-development-cockpit)`,
+      head: branchName,
+      base: baseBranch
+    })
+
+    console.log(`✅ Created PR #${pr.number}: ${pr.html_url}`)
+
+    return {
+      url: pr.html_url,
+      number: pr.number
+    }
+  }
+}

tests/services/github/pr.service.test.ts

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+import { GitHubPRService } from '@/services/github/pr.service'
+
+// Mock Octokit
+jest.mock('@octokit/rest', () => ({
+  Octokit: jest.fn().mockImplementation(() => ({
+    repos: {
+      createOrUpdateFileContents: jest.fn().mockResolvedValue({ data: {} }),
+      getBranch: jest.fn().mockResolvedValue({ data: { commit: { sha: 'abc123' } } })
+    },
+    git: {
+      createRef: jest.fn().mockResolvedValue({ data: {} })
+    },
+    pulls: {
+      create: jest.fn().mockResolvedValue({
+        data: {
+          html_url: 'https://github.com/owner/repo/pull/1',
+          number: 1
+        }
+      })
+    }
+  }))
+}))
+
+describe('GitHubPRService', () => {
+  let service: GitHubPRService
+
+  beforeEach(() => {
+    service = new GitHubPRService('fake-token')
+  })
+
+  it('should create a pull request', async () => {
+    const result = await service.createPullRequest({
+      owner: 'testowner',
+      repo: 'testrepo',
+      branchName: 'feature/ai-generated',
+      baseBranch: 'main',
+      title: 'AI Generated Feature',
+      body: 'This PR contains AI-generated code',
+      files: [
+        { path: 'src/test.ts', content: 'console.log("test")' }
+      ]
+    })
+
+    expect(result.url).toBe('https://github.com/owner/repo/pull/1')
+    expect(result.number).toBe(1)
+  })
+})