Camera orientation in degrees: ui.camera and the MCP screenshot's camera

`ui.view` and the MCP `screenshot` tool only turned to the named views, so
a picture sequence could only cut between them. `Orientation` (render) is a
camera orientation in degrees, {yaw, pitch, distance?}, checked as hostile
input: angles finite, distance finite and above 0, yaw wrapped, pitch
clamped to ±90, distance to 0.001–1e9. `modelcraft_engine::view::orientation`
parses it from JSON for both callers:

- control channel `ui.camera {yaw, pitch, distance?}` turns the app's camera;
- MCP `screenshot {camera}` turns it first (bridged through `ui.camera`,
  headless in the CPU render, framed unless a distance is given). `view` and
  `camera` are not given together.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm

crates/render/src/lib.rs

@@ -11,7 +11,7 @@ mod display;
 mod raster;
 mod vec;
 
-pub use camera::{Camera, Mat4, StandardView};
+pub use camera::{Camera, Mat4, Orientation, StandardView};
 pub use display::{DisplayEdge, DisplayLine, DisplayMesh, DisplayNode, DisplayTri, SurfaceTri};
 pub use raster::{
     Canvas, MAX_DIM, MAX_PIXELS, MAX_PRIMITIVES, RenderError, Rgb, Scene, SceneLine, ScenePoint, SceneTri, fit_size, png, render, render_png, shade,