[Bug]: devcontainer post-create.sh fails on Kiro CLI 404, blocking uv, DocFx, Kimi and CodeBuddy installs

### Bug Description

The post-create.sh script exits early when Kiro CLI installation fails with a 404 error, everything after Kiro is never installed: uv, DocFx, Kimi CLI, and CodeBuddy.

### Steps to Reproduce

1. Clone spec-kit
2. Open in VS Code → "Dev Containers: Open Folder in Container..."
3. Wait for container build to complete

### Expected Behavior

All tools defined in post-create.sh are installed, even if Kiro CLI installation fails.

### Actual Behavior

The script stops at Kiro CLI and never installs uv, DocFx, Kimi CLI, and CodeBuddy.

### Specify CLI Version

uv not installed ...

### AI Agent

Not applicable

### Operating System

macos 26.5

### Python Version

uv was never installed due to this bug

### Error Logs

```shell
🤖 Installing Kiro CLI...
[ERROR] Command failed (Exit Code 22): curl -fsSL "https://kiro.dev/install.sh" -o "/tmp/tmp.IxPtRpp6RF"
curl: (22) The requested URL returned error: 404
[468580 ms] postCreateCommand from devcontainer.json failed with exit code 22. Skipping any further user-provided commands.
```

### Additional Context

Confirmed the issue is not network-related:

```
vscode ➜ /workspaces/spec-kit (main) $ curl -fsSL "https://kiro.dev/install.sh" -o /tmp/test-kiro.sh; echo "Exit code: $?"
curl: (22) The requested URL returned error: 404
Exit code: 22
vscode ➜ /workspaces/spec-kit (main) $ curl -fsSL "https://google.com" -o /dev/null && echo "OK"
OK
```