Agent View ignores remote container context when workspace is opened in ssh dev container

### Describe the bug

## Description

When a VS Code workspace is opened in a remote SSH dev container, the new Copilot Agent View incorrectly initializes on the host system instead of inside the container, ignoring the remote context that the main Chat interface correctly respects.

## Expected Behavior

- Workspace opened in dev container → Chat works correctly in container
- New Agent View opened → should also run in the same container context
- Both interfaces should respect the remote container environment

## Actual Behavior

- Workspace opened in dev container → Chat works correctly in container
- New Agent View opened → **starts on the host system instead of the container**
- Agent has file system access to the host (e.g., `/Users//...`) instead of container paths
- This creates a context mismatch and prevents proper interaction with container-specific tools/dependencies

## Environment

- OS: macOS (Darwin)
- Workspace: SSH remote dev container
- VS Code: Remote - Containers extension enabled
- Copilot CLI: Latest version

## Impact

- Agent cannot access container-specific dependencies/tools
- Workspace context is fragmented between Chat (container) and Agent (host)
- Potential security/privacy issue: agent operates on host file system when it shouldn't

## Suggested Fix

Agent View should automatically detect and respect the VS Code remote context (dev container, SSH, WSL, etc.) on initialization, matching the behavior of the main Chat interface.

### Affected version

latest

### Steps to reproduce the behavior

1. Open a project in a dev container (e.g., via Remote - Containers extension)
2. Verify Chat interface works correctly in container
3. Open Agent View (or new agent session)
4. Check working directory/system info: `echo $PWD` or equivalent
5. **Observe:** Agent is on host system, not in container

### Expected behavior

- Workspace opened in dev container → Chat works correctly in container
- New Agent View opened → should also run in the same container context
- Both interfaces should respect the remote container environment

### Additional context

_No response_

まず、記載されている SSH 開発コンテナーの手順で問題を再現し、Chat と Agent View の初期化を比較して、`echo $PWD` で作業ディレクトリを確認します。Agent View が実行コンテキストを確立する場所を追跡し、それを Chat のメインインターフェースと比較します。Agent View がコンテナー内で実行され、そのパス、ツール、依存関係にホストではなくアクセスできれば完了です。

索引モデルが issue の本文から書いたものです。