Agent Debug Logs resolves Agent Host ID instead of Copilot SDK conversation ID

Does this issue occur when all extensions are disabled?: Yes

### Summary

For Copilot Agent Host sessions, **Agent Debug Logs can show only the VS Code-side `Instructions Discovery` and `Hook Discovery` rows even though the underlying Copilot SDK session has a complete `events.jsonl` journal. The panel resolves the event journal using the Agent Host session ID, but the SDK persists that logical chat under a different SDK conversation ID.

### Environment

- VS Code `1.135.0` (`08d4889f9ec4a1685d257b9b95de036c8e1ce1e5`)
- macOS arm64
- Copilot running as the local Agent Host `copilotcli` provider (`agent-host-copilotcli`)
- `"chat.agentHost.agentDebugLog.enabled": true`

### Reproduction

1. Start a new VS Code Copilot Agent Host session (the SDK-backed Copilot / `agent-host-copilotcli` harness).
2. Send a request that produces normal model and/or tool activity.
3. Open **Agent Debug Logs** for that session.

### Actual result

The Logs view contains only the initial client-side customization-discovery events, for example:

```text
Instructions Discovery
Hook Discovery
```

There are no user-message, LLM, tool-call, tool-result, or agent-response events, and the panel does not show an error.

### Expected result

The panel should resolve the backing Copilot SDK conversation and render the event stream from its `events.jsonl`, including model and tool events.

### Investigation / suspected root cause

This was verified without exposing the contents of any prompts or tool payloads:

- The Agent Debug Logs breadcrumb identified the logical Agent Host session as `agent-host-copilotcli:/`.
- The VS Code per-session metadata at `agentSessionData//session.db` stored a **different** SDK conversation ID in `defaultChatProviderData`.
- The SDK event journal existed at `~/.copilot/session-state//events.jsonl`; it contained 821 ordered events at the time of inspection and referenced the Agent Host session.
- No `~/.copilot/session-state//events.jsonl` existed.

The debug provider appears to derive the journal location directly from the URI path via `getCopilotCliSessionRawId(sessionResource)` and then reads:

```text
~/.copilot/session-state//events.jsonl
```

When that file is absent, `AgentHostChatDebugContribution._provideChatDebugLog` returns `undefined`, so only events emitted independently by the VS Code client remain visible.

However, the Agent Host Copilot implementation already distinguishes the logical host session from its backing SDK conversation (`sdkConversationId`). The debug-log path resolution needs the same mapping instead of assuming that the host-session URI ID is the SDK conversation ID.

Relevant code:

- `src/vs/workbench/contrib/chat/browser/chatDebug/agentHostChatDebugProvider.ts`
- `src/vs/workbench/contrib/chat/browser/copilotCliEventsUri.ts`
- `src/vs/platform/agentHost/node/copilot/copilotAgent.ts`

### Suggested fix

Resolve the backing SDK conversation ID for the active Agent Host chat/session first, then load `events.jsonl` from that SDK session directory. Ideally, make this an Agent Host/provider API rather than duplicating local filesystem and ID-resolution assumptions in the debug-panel provider. The same resolution should work for local, adopted/migrated, multi-chat, and remote Agent Host sessions.

### Impact

This makes Agent Debug Logs, `#debugEventsSnapshot`, and `/troubleshoot` largely unusable for affected VS Code-hosted Copilot sessions, while the exact same Copilot SDK/CLI session has a complete journal on disk.