bug: Ideogram 4 frontend generation saves unused steps/cfgScale in metadata and does not recall sampler preset or overrides #10140

What happened?

When generating with Ideogram 4 from the frontend Generate tab (webv2), selecting a different Sampler Preset (V4_QUALITY_48 = 48 steps, V4_DEFAULT_20 = 20 steps, V4_TURBO_12 = 12 steps) or toggling the Ideogram 4 Steps / Guidance / Mu overrides runs ideogram4_denoise with the chosen preset/overrides, but the saved image metadata and metadata recall have three related issues:

1. core_metadata records the unused top-level settings.steps and settings.cfgScale sliders instead of the effective Ideogram 4 preset/override values:

   • In invokeai/frontend/webv2/src/features/generation/core/graph.ts (buildIdeogram4Graph, lines 1828–1863), ideogram4_denoise is wired with sampler_preset: settings.ideogram4SamplerPreset and optional steps: settings.ideogram4Steps, guidance_scale: settings.ideogram4GuidanceScale, and mu: settings.ideogram4Mu. It never uses the generic settings.steps or settings.cfgScale fields.
   • However, addMetadata in invokeai/frontend/webv2/src/features/generation/core/graphBuilder.ts (lines 151–169) always writes steps: settings.steps and cfg_scale: settings.cfgScale, and buildIdeogram4Graph does not override steps or cfg_scale with the effective preset/override values.
   • Additionally, in GenerateRenderSection.tsx (lines 639–677, 727, 752), the generic Steps and CFG Scale scrubbers (and header badge) remain visible and editable for ideogram-4 even though buildIdeogram4Graph ignores them in favor of <Ideogram4SamplingFields>.

2. When ideogram4Steps, ideogram4GuidanceScale, and ideogram4Mu overrides are left off (null, i.e. derived from the preset), the preset's effective values are not reflected in steps / cfg_scale:

   • Selecting Turbo (12 steps) (V4_TURBO_12) or Default (20 steps) (V4_DEFAULT_20) runs 12 or 20 steps in ideogram4_denoise, while metadata.steps still records 48 (or whatever the unused top-level settings.steps slider held).

3. imageRecall.ts does not recall ideogram4_sampler_preset, ideogram4_steps, ideogram4_guidance_scale, ideogram4_mu, or ideogram4_color_palette:

   • In invokeai/frontend/webv2/src/workbench/image-actions/imageRecall.ts (getMetadataModelTuning, lines 539–613), per-family tuning recall handles flux, z-image, qwen-image, krea-2, moss-image, and anima, but has no handler for model.base === 'ideogram-4'.
   • Clicking Recall All or Remix on an Ideogram 4 image only restores values.steps and values.cfgScale (the inert sliders) and does not restore ideogram4SamplerPreset, ideogram4Steps, ideogram4GuidanceScale, ideogram4Mu, or ideogram4ColorPalette.

(Note: In PR #10083, Ideogram4DenoiseInvocation._build_metadata() on the backend already computes steps and cfg_scale/guidance from PRESETS[self.sampler_preset] and any active steps/guidance_scale/mu overrides, so once frontend graph builders drop core_metadata or buildIdeogram4Graph / imageRecall.ts are updated, the saved and recalled values will match what actually ran.)