Fix bypassPermissions silent failure (Issue #30)

[ltawfik]

Summary

Fixes #30 - When permission_mode='bypassPermissions' fails, users experience a silent failure where their async iterator completes without yielding any messages.

Problem

Users report "no response is received and the program terminates" when using bypassPermissions. The async for loop completes without executing its body, making it appear as if nothing happened.

Root Causes

1. CLI version incompatibility - Older CLIs don't recognize --permission-mode flag
2. Root user restriction - Security check prevents bypassPermissions when running as root
3. Disabled in settings - Falls back to interactive mode when disabled
4. Other security restrictions - Various scenarios causing the CLI to exit without output

Solution

This PR adds comprehensive error detection that transforms silent failures into clear, actionable error messages:

• Tracks whether ANY output was received (_received_any_output)
• Checks stderr for specific error patterns
• Provides different error messages for different failure modes
• Adds --debug flag for bypassPermissions to capture more diagnostics
• Updates entrypoint to 'sdk-cli' for better CLI integration

Changes

• subprocess_cli.py: Enhanced error detection and reporting
• test_transport.py: Added comprehensive tests for all failure scenarios

Test Plan

• Added unit tests for all error scenarios
• Manually tested with old CLI version
• Verified error messages are clear and actionable
• All existing tests pass

Example

Before (silent failure):

async for message in query(prompt="test", options=ClaudeCodeOptions(permission_mode="bypassPermissions")):
    print("Got message\!")  # This never executes, confusing users

After (clear error):

ProcessError: Claude Code CLI terminated without producing any output when using bypassPermissions mode. This can happen when:
1. Running as root/sudo (security restriction)
2. bypassPermissions is disabled in settings
3. Other security restrictions are in place

Try using permission_mode='acceptEdits' instead, which is the recommended mode for SDK usage.

🤖 Generated with Claude Code