GitHub Copilot Chat in WSL experiences 40-80 second startup delays due to CopilotCLIChatSessionContentProvider.listSessions

### Describe the bug

## Environment

* VS Code: 1.122.1
* GitHub Copilot Chat: 0.50.1
* WSL: Ubuntu
* OS Host: Windows 11
* Copilot account: Educational quota
* Remote Development: WSL

## Description

GitHub Copilot Chat takes approximately 40-80 seconds to become available when running inside WSL.

The delay is reproducible across VS Code restarts and occurs even after:

* Clearing Copilot state
* Clearing workspace storage
* Reinstalling Copilot Chat
* Disabling local indexing
* Reducing workspace index size
* Disabling memory features
* Disabling MCP features
* Optimizing Git settings
* Verifying filesystem permissions

The extension itself activates quickly, but startup appears blocked by `CopilotCLIChatSessionContentProvider.listSessions`.

## Observed Logs

```text
ConversationFeature: Waiting for copilot token

[CopilotCLIChatSessionContentProvider] listSessions took 40514ms

Logged in as

Got Copilot token

Copilot Chat: 0.50.1

Failed to create database. Falling back to in-memory db: Error: unable to open database file
```

Subsequent calls are fast:

```text
[CopilotCLIChatSessionContentProvider] listSessions took 14ms
[CopilotCLIChatSessionContentProvider] listSessions took 38ms
[CopilotCLIChatSessionContentProvider] listSessions took 5ms
```

The large delay occurs only once during startup.

## What Has Been Verified

### Extension activation is not the problem

VS Code reports:

```text
GitHub Copilot Chat
Activation: 2348ms
```

### Network is not the problem

```bash
time curl -I https://api.github.com
```

Result:

```text
real 0m0.174s
```

### Session database is tiny

```text
session-store.db 4 KB
session-store.db-shm 32 KB
session-store.db-wal 149 KB
```

### Session state is tiny

```bash
du -sh ~/.copilot/session-state
```

Result:

```text
4.0K
```

### Workspace indexing does not affect the issue

Tested:

```json
"github.copilot.chat.localIndex.enabled": false
"github.copilot.chat.workspace.maxLocalIndexSize": 100
```

No measurable improvement.

### Git is not the problem

Git operations complete in milliseconds and repository scanning is fast.

## Additional Observation

Copilot reports:

```text
Failed to create database. Falling back to in-memory db.
```

However, Copilot successfully creates:

```text
~/.vscode-server/data/User/globalStorage/github.copilot-chat/session-store.db
~/.vscode-server/data/User/globalStorage/github.copilot-chat/session-store.db-wal
~/.vscode-server/data/User/globalStorage/github.copilot-chat/session-store.db-shm
```

which suggests the failing database may be a different internal store.

## Expected

Copilot Chat should become available within a few seconds, similar to Codex and other AI extensions running in the same WSL environment.

## Actual

Copilot Chat consistently requires 40-80 seconds before becoming usable due to an extended `listSessions` operation during startup.

## Reproducibility

100% reproducible across restarts.

### Affected version

_No response_

### Steps to reproduce the behavior

_No response_

### Expected behavior

_No response_

### Additional context

_No response_