Claude Opus 4.7 missing from ACP model list (hardcoded model registry only includes up to Opus 4.6)

## Description

Claude Opus 4.7 has been generally available since April 16, 2026 and is accessible via the Anthropic API, Claude Code CLI, Claude.ai, Bedrock, Vertex AI, and Foundry. However, the `@anthropic-ai/claude-agent-sdk` npm package (tested versions 0.2.83 and 0.2.131) does not include `claude-opus-4-7` in its hardcoded model registry.

## Steps to reproduce

1. Install `@zed-industries/claude-agent-acp@0.23.1` (latest)
2. Start an ACP session and request the available models
3. Observe that `claude-opus-4-6` is the newest Opus model listed
4. `claude-opus-4-7` is absent

## Evidence

Searching the SDK source confirms the model is missing:

```bash
# SDK 0.2.131 (latest on npm as of 2026-05-06)
grep -oE "claude-opus-4-[0-9a-zA-Z@_.-]+" node_modules/@anthropic-ai/claude-agent-sdk/cli.js | sort -u
```

Output:
```
claude-opus-4-0
claude-opus-4-1
claude-opus-4-1-20250805
claude-opus-4-1-20250805-v1
claude-opus-4-1@20250805
claude-opus-4-20250514
claude-opus-4-20250514-v1
claude-opus-4-5
claude-opus-4-5-20251101
claude-opus-4-5-20251101-v1
claude-opus-4-5@20251101
claude-opus-4-6
claude-opus-4-6-v1
```

No `claude-opus-4-7` entry.

## Expected behavior

`claude-opus-4-7` should be available in the ACP model list, consistent with its GA status across all other Anthropic platforms.

## Environment

- `@anthropic-ai/claude-agent-sdk`: 0.2.131 (also tested 0.2.83)
- `@zed-industries/claude-agent-acp`: 0.23.1
- Claude Code CLI: has Opus 4.7 available
- OS: macOS