v0.4.0

Added

• Pictures on the ChatGPT sign-in (Rho.Images.generate/2): the
  user's ChatGPT Plus/Pro sign-in (:openai_codex) draws a picture as
  Codex does, through the Codex Responses endpoint with OpenAI's hosted
  image_generation tool, from words and optional reference pictures
  (an edit). It returns the bytes, type, the tool's revised prompt, size
  and action; options :size, :quality, :format, :references,
  :model, :timeout (the whole drawing, 4 minutes by default; the
  stream is parsed as it arrives, bounded). No API key and no per-picture
  bill: it counts against the subscription's Codex limits, recorded in
  Rho.Usage like a model call
  (tokens, windows, a 429's reset). Errors are Rho.LLM.error/0s. A
  focused Req call: req_llm's openai_codex provider drops the
  image_generation_call item and, for the gpt-5.6 models, strips hosted
  tools from the request.
• Rho.Images.models/1: the Codex models the ChatGPT account may use
  (Codex's GET /backend-api/codex/models). The driving model defaults
  to gpt-5.6-luna; when the account refuses a model (gpt-5.5 and
  gpt-image-2 are refused), generate/2 draws once with the first model
  that list gives (Codex's default).