Summary

Add a bundled codex-cli image generation backend so Hermes can use Codex CLI's built-in image generation through the user's local Codex/ChatGPT login.

What this changes

• add plugins/image_gen/codex_cli backend
• detect availability via codex login status
• resolve CODEX_HOME from env, config, or default ~/.codex
• run generation through codex exec --json --full-auto --enable image_generation
• discover generated image files from thread output or newly created files
• add focused provider tests for success/error paths and config/env handling

Sample config

image_gen:
  provider: codex-cli
  model: codex-cli-default
  codex_cli:
    codex_home: ~/.codex-hermes

Files touched

• plugins/image_gen/codex_cli/__init__.py
• plugins/image_gen/codex_cli/plugin.yaml
• tests/plugins/image_gen/test_codex_cli_provider.py

Validation

• pytest -q tests/plugins/image_gen tests/agent/test_image_gen_registry.py tests/hermes_cli/test_plugin_scanner_recursion.py tests/tools/test_image_generation.py tests/tools/test_image_generation_env.py
• 126 passed