generate_3d: 3D models with fal.ai (image, text, or image steered by text)

- New tool: image-to-3D (project file or an image attached to the chat,
  optional back/left/right views) or text-to-3D; image + prompt refines the
  image with the prompt first (the 3D models take no text with an image).
  Styles textured / geometry / lowpoly, optional PBR, face count. Runs through
  fal.ai's queue API with progress, saves GLB + preview, books the cost
  (published prices, overridable per model). Request bodies for the Hunyuan3D,
  Tripo and Trellis families; defaults [images] model_3d / model_3d_text.
- Chat card: "Open in the 3D view"; media overview: kind "model" (also
  STL/3MF/OBJ written by agents) with previews.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -3,6 +3,20 @@
 All notable changes to CodeCraft. Versions follow [Semantic Versioning](https://semver.org/);
 until 1.0, minor versions may contain breaking changes.
 
+## [Unreleased]
+
+### Added
+
+- **3D models with fal.ai (`generate_3d`):** from an image (a project file or one pasted into the
+  chat, optional back/left/right views), from a text prompt, or from an image steered by a prompt
+  (the image is refined with the prompt first – the 3D models take no text with an image).
+  Styles textured, geometry (untextured, for 3D printing) and low-poly, optional PBR. Uses fal.ai's
+  queue (takes minutes, with progress), saves a GLB plus a preview image, books the cost.
+  Defaults: Hunyuan3D v3 image-to-3D / text-to-3D (`[images] model_3d`, `model_3d_text`); Tripo
+  and Trellis endpoints work too.
+- The chat card offers "Open in the 3D view"; the media overview lists 3D models (also STL/3MF
+  written by the agent) with their previews.
+
 ## [v202611-00023] – 2026-11-12
 
 ### Added