"Send to a new session" should trigger the create_session tool

### Problem

When a user sends the message **"Send to a new session"** during an agent conversation, the agent responds with a text handoff summary instead of actually creating a new session.

Had a plan open for approval

### Expected

The message should trigger a `create_session` tool call to create a new session in the VS Code workspace (optionally seeded with the handoff context), rather than only producing text output.

### Actual

The agent emitted a handoff summary as plain text; no `create_session` tool call was made, so no new session was created.

### Notes

- Repro is intent-based: the phrase "Send to a new session" (and similar) should be recognized as a request to spin up a new session via `create_session`.
- Plan/content specifics of the originating conversation are intentionally omitted.