feat: add Ideogram 4.0 image provider

[balalofernandez]

Summary

Adds a new ideogram image provider (Ideogram 4.0 / v4) alongside the existing Gemini and OpenAI providers, configured the same way via environment variables.

• New provider client (src/api/ideogramImageClient.ts): createIdeogramImageClient calls the v4 /v1/ideogram-v4/generate endpoint with Api-Key auth and a text_prompt multipart request, then downloads the ephemeral image URL into a Buffer. Follows the same ImageClient/Result patterns as the OpenAI client.

• Config: new IDEOGRAM_API_KEY env var + validation, gated on IMAGE_PROVIDER=ideogram (mirrors the Gemini/OpenAI key handling).

• Wiring: mcpServer routes to the Ideogram client when configured; since v4 enhances prompts natively (magic-prompt), the external text-model pipeline is skipped — no separate text client or API key required.

• IMAGE_QUALITY controls resolution + speed: the preset maps to rendering_speed (TURBO/DEFAULT/QUALITY) and selects the v4 resolution. aspectRatio chooses the orientation only, since v4 ties resolution to aspect ratio (every v4 resolution is ~4 MP).

  IMAGE_QUALITY	Landscape	Portrait	Square
  fast	2560x1440	1440x2560	2048x2048
  balanced	2304x1728	1728x2304	2048x2048
  quality	2496x1664	1664x2496	2048x2048

• Unsupported on v4 (rejected with clear errors): useGoogleSearch and image-to-image editing — use Gemini/OpenAI for those.

• Docs (README.md, server.json) updated.

Notes / caveats (v4 API design, not implementation)

• Square is fixed: v4 has a single square resolution, so for 1:1 / default orientation the preset changes speed but not size.
• Small size range: all v4 resolutions sit at ~3.7–4.2 MP (~12% spread) — the max v4 exposes; rendering_speed remains the stronger fidelity lever.
• v3 was intentionally not used (lower quality), per request.

Testing

• tsc build, Biome check/lint, dependency-cycle, and knip all pass.
• Full suite: 253 tests pass (17 files), including new ideogramImageClient tests and an Ideogram provider-routing test.
• Not exercised against the live Ideogram API (no key in this environment); request/response shape is based on the v4 docs and covered by mocked tests.

[shinpr]

Thanks for this. A few points before it can move forward.

The core value of this MCP is creating a structured prompt and generating an image from it. So adding a new image model means the prompt-optimization policy and quality level have to be aligned across providers. When GPT-Image-2 was added, we evaluated that the optimized prompt was equivalent in quality, speed, and cost.

As a prerequisite, please verify against the live API. We can't merge anything that hasn't been verified end to end.

On magic-prompt: with it ON, generation depends entirely on magic-prompt, whose output isn't visible. So if you want it ON, please confirm and evaluate that magic-prompt's prompt is equivalent or better, or attach evidence. Otherwise, optimize the prompt on the MCP side and use AUTO to let magic-prompt add on top of it. As a note, the docs list an OFF option, so disabling it looks possible.