TaskType enum missing AGENT, GET_AGENT_CARD, CANCEL_AGENT, PULL_WORKFLOW_MESSAGES

## Summary

Four task types added to the Conductor server in 3.32.0-rc.9 (conductor-oss/conductor PR #1288)
are absent from the `TaskType` enum in `src/open-api/types.ts`. Users cannot reference
these types via the SDK without using raw strings.

## Server baseline

Conductor **3.32.0-rc.9**

## Missing values

Server `TaskType.java` has:
```java
PULL_WORKFLOW_MESSAGES,
AGENT,
GET_AGENT_CARD,
CANCEL_AGENT;
```

All four are absent from the SDK `TaskType` enum.

## Evidence

**Static:** `TaskType` enum in `types.ts` ends at `LIST_MCP_TOOLS`. All four values absent.

**Live (2026-07-16):** A raw task with `"type": "AGENT"` was registered against
Conductor OSS 3.32.0-rc.9. Server accepted the definition — the gap is SDK-only.

## Proposed fix

Add to `TaskType` enum in `src/open-api/types.ts`:
```typescript
PULL_WORKFLOW_MESSAGES = "PULL_WORKFLOW_MESSAGES",
AGENT = "AGENT",
GET_AGENT_CARD = "GET_AGENT_CARD",
CANCEL_AGENT = "CANCEL_AGENT",
```

Builder functions for AGENT, GET_AGENT_CARD, and CANCEL_AGENT should follow once the
agent task API is stable.

## Related

Discovered during systematic SDK audit against Conductor OSS 3.32.0-rc.9.
Server PR: conductor-oss/conductor#1288
Same gap in Java SDK (conductor-oss/java-sdk#135) and Python SDK (conductor-oss/python-sdk#431).

src/open-api/types.ts を開き、現在 LIST_MCP_TOOLS で終わっている TaskType enum を確認します。issue に記載されている 4 つのサーバー値を追加し、その後 TypeScript SDK がビルドされ、4 つの名前すべてを raw string なしで参照できることを確認します。

索引モデルが issue の本文から書いたものです。