Failed to spawn Bun process: E2BIG argument list too long in Claude PR Assistant workflow

**Describe the bug**
The Claude PR Assistant workflow fails with the error: `Error: Failed to spawn Claude Code process: E2BIG: argument list too long, posix_spawn 'bun'`. This appears when running Bun with a large argument list, causing the job to fail.

**To Reproduce**
Steps to reproduce the behavior:

1. Trigger the Claude PR Assistant workflow on a pull request with large file changes or prompts.
2. Wait for the Claude-related job to start.
3. Observe the log output during the Bun process execution.
4. See error: `E2BIG: argument list too long, posix_spawn 'bun'`

**Expected behavior**
The workflow should complete successfully without hitting argument list limitations when invoking Bun. Large inputs or file lists should be handled gracefully by writing to temporary files or batching.

**Screenshots**
If applicable, you may want to include a screenshot of the error log:
```
Error: Failed to spawn Claude Code process: E2BIG: argument list too long, posix_spawn 'bun'
```

**Additional context**
- The error was observed in the `.github/workflows/claude.yml` workflow. (written based on official docs)
- Possibly triggered by a large prompt or file list being passed as arguments to Bun.
- Related log output:
```
Error during Claude execution: Failed to spawn Claude Code process: E2BIG: argument list too long, posix_spawn 'bun'
```
- Suggest investigating if arguments can be passed via a temp file or reduced in size.