Faut-il créer votre propre Midjourney ?

Build me a local image-generation studio wrapping open models, in place of
Midjourney. Requirements:

- A local web app (Node + Express, plain HTML/JS) on localhost:4890: prompt box,
  a generate-4 button, and a gallery grid of results.
- Backend targets whichever engine I have: a local ComfyUI instance running Flux
  or SDXL if there is a GPU, otherwise a hosted API like Replicate or fal.ai
  (key in .env). Same UI either way.
- Save every image to ~/ImageGen/YYYY-MM/ with a sidecar JSON: prompt, seed,
  model, steps, so any result is reproducible later.
- Gallery search over past prompts via SQLite FTS5, favorites, and one-click
  re-run with the same seed or a new variation.
- Style presets in a styles.json of prompt prefixes and suffixes I can toggle,
  a poor man's style reference.
- No accounts, no telemetry, everything stays local except the hosted-API calls.
- Out of scope: training or fine-tuning models, and matching Midjourney's look.
  Build for reproducibility and control, not a taste layer.
- README: both engine setups, the rough cost per image on the hosted route, and
  a plain note that this is not Midjourney, the proprietary model and its years
  of aesthetic tuning cannot be rebuilt, this trades that for privacy and control.