ci: migrate sdk-regenerate pipeline from autorest.go

Bring over the ARM SDK regeneration pipeline that produces regenerate PRs
against Azure/azure-sdk-for-go, replacing the real ARM service specs that
were removed from typespec-go's local test set. Supports both released and
dev (locally built) emitter modes, matching the original.

Adaptations for typespec-azure:
- checkout self as typespec-azure with submodules: recursive (core)
- build via root pnpm install + turbo build of @azure-tools/typespec-go...
  (emitter plus its in-repo workspace deps) instead of a single-package build
- add NodeVersion to globals.yml
- dev mode: read the emitter's generation-time dependency versions from the
  packed .tgz (where pnpm rewrites workspace: specifiers to concrete ranges)
  instead of the source package.json, so emitter-package.json gets valid
  published versions rather than workspace: specifiers

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: Copilot

eng/pipelines/sdk-regenerate.yml

@@ -0,0 +1,99 @@
+trigger: none
+pr: none
+
+schedules:
+  - cron: "0 2 * * 1" # Weekly at Monday 2 AM UTC
+    displayName: Weekly regenerate SDK
+    branches:
+      include:
+        - main
+
+parameters:
+  - name: UseLatestSpec
+    default: false
+    type: boolean
+  - name: ServiceFilter
+    type: string
+    default: '.*'
+  - name: UseDevPackage
+    default: false
+    type: boolean
+
+variables:
+  - template: /eng/pipelines/templates/variables/globals.yml
+  - template: /eng/pipelines/templates/variables/image.yml
+  - group: Release Secrets for GitHub
+
+pool:
+  name: $(LINUXPOOL)
+  demands: ImageOverride -equals $(LINUXVMIMAGE)
+
+resources:
+  repositories:
+    - repository: azure-sdk-for-go
+      type: github
+      name: Azure/azure-sdk-for-go
+      endpoint: azure
+      ref: main
+
+jobs:
+  - job: Generate_SDK
+
+    timeoutInMinutes: 120
+
+    steps:
+      - checkout: self
+        fetchDepth: 1
+        submodules: recursive
+      - checkout: azure-sdk-for-go
+
+      - task: NodeTool@0
+        displayName: 'Install Node.js $(NodeVersion)'
+        inputs:
+          versionSpec: '$(NodeVersion)'
+
+      - script: |
+          npm i -g corepack@latest
+          corepack enable
+          corepack prepare pnpm@latest-10 --activate
+        displayName: Install pnpm
+
+      - script: pnpm install
+        displayName: pnpm install
+        workingDirectory: $(Build.SourcesDirectory)/typespec-azure
+
+      # Build the emitter together with its in-repo workspace dependencies
+      # (TCGC, compiler via the core submodule, azure-resource-manager, etc.).
+      - script: pnpm turbo run --filter "@azure-tools/typespec-go..." build
+        displayName: pnpm build
+        workingDirectory: $(Build.SourcesDirectory)/typespec-azure
+
+      - script: pnpm pack
+        displayName: pnpm pack
+        workingDirectory: $(Build.SourcesDirectory)/typespec-azure/packages/typespec-go
+
+      - script: npm install -g @azure-tools/typespec-client-generator-cli
+        displayName: 'Install tsp-client'
+
+      - script: |
+          python3 $(Build.SourcesDirectory)/typespec-azure/eng/scripts/sdk_regenerate.py --sdk-root=$(Build.SourcesDirectory)/azure-sdk-for-go --typespec-go-root=$(Build.SourcesDirectory)/typespec-azure/packages/typespec-go --typespec-go-branch=$(Build.SourceBranchName) --use-latest-spec=${{ parameters.UseLatestSpec }} --service-filter="${{ parameters.ServiceFilter }}" --use-dev-package=${{ parameters.UseDevPackage }}
+        displayName: 'Generate SDK'
+        workingDirectory: $(Build.SourcesDirectory)/azure-sdk-for-go
+
+      - template: /eng/common/pipelines/templates/steps/login-to-github.yml@azure-sdk-for-go
+        parameters:
+          ScriptDirectory: $(Build.SourcesDirectory)/azure-sdk-for-go/eng/common/scripts
+
+      - template: /eng/common/pipelines/templates/steps//create-pull-request.yml@azure-sdk-for-go
+        parameters:
+          WorkingDirectory: $(Build.SourcesDirectory)/azure-sdk-for-go
+          ScriptDirectory: $(Build.SourcesDirectory)/azure-sdk-for-go/eng/common/scripts
+          RepoName: azure-sdk-for-go
+          PROwner: Azure
+          BaseBranchName: 'refs/heads/main'
+          PRBranchName: typespec-go-regenerate-$(Build.SourceBranchName)
+          CommitMsg: 'Regenerate SDK based on typespec-go branch $(Build.SourceBranchName)'
+          PRTitle: '[Automation] Regenerate SDK based on typespec-go branch $(Build.SourceBranchName)'
+          OpenAsDraft: 'true'
+          PushArgs: '--force'
+          AuthToken: $(GH_TOKEN)

eng/pipelines/templates/variables/globals.yml

@@ -1,3 +1,6 @@
 variables:
   # Disable CodeQL by default to prevent build timeouts
   Codeql.SkipTaskAutoInjection: true
+  # Node.js version used by pipelines that install Node via NodeTool (e.g. the
+  # typespec-go SDK regeneration pipeline).
+  NodeVersion: "24.x"