[cherry-pick] chat: fix GitHub context repository selection

[vs-code-engineering]

Summary

Cherry-pick of #334594 for release/1.137.

Fix GitHub issue and pull request attachments in both the Agents window and the editor chat context picker:

• keep searches scoped to the selected workspace folder while Git discovery is still loading
• preserve distinct folder choices in multi-root workspaces, including multiple roots of the same repository
• pass unresolved local folder URIs to Copilot Chat so it can resolve the repository directly
• read remotes from .git/config without waiting for repository HEAD state
• support Git worktrees and symlinked Git directories
• prefer an already-open repository's established remote ordering before falling back to direct config reads

Cherry-pick notes

The source change overlapped with release/1.137 updates in the chat and Sessions providers. The conflicts were reconciled against the release branch, and the follow-up review findings around single-folder fallback, symlink bit flags, and upstream-before-origin ordering are included.

Validation

• ESLint on the changed files
• npm run transpile-client
• targeted chat and Sessions tests (93 passing)
• targeted Copilot Chat unit tests (38 passing)
• Copilot Chat extension typecheck
• component explorer production build

Fixes #334603

[Copilot]

🟡 Changes recommended

Committed conflict markers prevent compilation, and repository scoping and remote ordering still have unresolved edge cases.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

Cherry-picks fixes for repository-scoped GitHub issue and pull request attachments across Chat and Agents.

Changes:

• Adds workspace-aware repository selection.
• Resolves Git remotes directly, including worktrees.
• Adds regression coverage for repository-resolution scenarios.

File summaries

File	Description
chatContext.ts	Adds GitHub context pickers.
chatContext.test.ts	Tests repository selection.
copilotChatSessionsProvider.ts	Resolves Agents repository context.
copilotChatSessionsProvider.test.ts	Tests Agents context browsing.
gitServiceImpl.ts	Reads and orders local Git remotes.
copilotCloudSessionsProvider.ts	Resolves folder arguments to repositories.
copilotCloudSessionsProvider.spec.ts	Tests folder resolution and fallback.

Review details

Files not reviewed (1)

• extensions/copilot/package-lock.json: Generated file

Suppressed comments (4)

src/vs/workbench/contrib/chat/test/browser/actions/chatContext.test.ts:37

• This unresolved marker block prevents the newly added test helpers from parsing. Resolve it and add the helper dependencies (IGitRepository, IGitService, and observableValue) to the reconciled imports.
  src/vs/workbench/contrib/chat/test/browser/actions/chatContext.test.ts:134
• This additional conflict marker around the incoming tests keeps the suite syntactically invalid. Remove the markers while retaining the intended regression cases.
  src/vs/workbench/contrib/chat/browser/actions/chatContext.ts:112
• This second unresolved conflict block also leaves the class/contribution boundaries ambiguous and the file unparsable. Reconcile the incoming GitHub picker with the target branch rather than retaining either marker side verbatim.
  src/vs/sessions/contrib/providers/copilotChatSessions/browser/copilotChatSessionsProvider.ts:2651
• This committed conflict marker leaves two implementations in the method and makes the provider unparsable. Resolve all marker blocks in this file before merging.

• Files reviewed: 83/85 changed files
• Comments generated: 9
• Review effort level: Balanced

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[vs-code-engineering]

📬 CODENOTIFY

The following users are being notified based on files changed in this PR:

Ladislau Szomoru (@lszomoru)

Matched files:

• build/azure-pipelines/product-build-ado-ci.yml

TylerLeonhardt

Matched files:

• src/vs/platform/agentHost/node/claude/claudeAgent.ts