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 <[email protected]>
Claude-Session: https://claude.ai/code/session_01NmAttHhUZTokgPeEJia8sm

docs/control-protocol.md

@@ -39,6 +39,7 @@ same registry. `file.sample {name}` opens a sample (`parts`, `cantilever`, `impa
 | `ui.inspect` | — | view settings (`ui`), camera, viewport rect (points), renderer (`gpu`/`cpu`) and adapter, open command form, status bar, node and element counts, the results display (`results`: what the `results.*` commands reply: view, `stale`, contour range, modes), the probed node (`probe`), `busy` (the background job: a file opening, a solve), `prompt` (`{"unsaved": path}`, `"recover"`, `"samples"`), `recent` (recent files), `selected` (the browser's selected definition), `nav` (the left-drag mode), `layout` (each region of the window drawn last frame as `[x, y, w, h]` in points: `app_bar`, `ribbon`, `workspace_switcher`, `document_tab`, `app_bar:<action>`, `browser`, `viewport`, `nav_bar`, `axis_view`, `context`, `command_line`, `timeline`, `toolbar_dropdown`, `palette`), version |
 | `ui.set` | any view setting: `style` (`shaded_edges`, `shaded`, `wireframe`), `show_nodes`, `show_geometry`, `show_mesh`, `perspective`, `dark`, `show_tree` (the browser), `show_timeline`, `workspace` (`prepare`, `model`, `analysis`, `results`), `tab` (the toolbar tab: `geometry`, `mesh`, `properties`, `assembly`, `steps`, `loads`, `interactions`, `solve`, `results`, `tools`; a tab of another workspace brings that workspace), `palette` (the command search open), `menu` (the open menu: `file`, `help`, `workspace`, `view`, `more`, or a panel's drop-down as `<tab>/<panel>` such as `mesh/Tet`; `null` closes it) | an unknown setting or value is an error; returns the settings |
 | `ui.view` | `view`: `front`, `back`, `left`, `right`, `top`, `bottom`, `iso`, `home` (iso and fit), `fit` | returns the camera |
+| `ui.camera` | `yaw`, `pitch` (degrees), `distance?` (model units) | turns the camera to any orientation about its target: `yaw` about Z (0 looks along +Y, the front view; −45 is the iso view's, −90 the right view's), `pitch` the elevation above the XY plane; `distance` moves the eye (the zoom of an orthographic view). Angles must be finite and the distance above 0: the yaw is wrapped, the pitch clamped to ±90 and the distance to 0.001–10⁹; anything else is an error. A sequence of calls orbits smoothly. Returns the camera (`ui.inspect`'s, angles in radians) |
 | `ui.toolbar` | — | the ribbon: `workspace`, `workspaces`, `tab`, `tabs` (the workspace's), `menu` (the open menu), `panels` (each panel label's `menu` key and `rect`), and every catalogue entry (docs/features.md) with `id`, `label`, `tab`, `panel`, `command` (null while coming soon), `more` (its related commands), `coming_soon` (the milestone, or null), `fit` — `full` (a button), `collapsed` (its panel is one button), `more` (its panel is in the » menu) or `menu` (in its panel's drop-down) — and `rect` (screen points, last frame, on the shown tab; for `menu` entries the row while the drop-down is open) |
 | `ui.start` | `command`: a command or toolbar entry id | like a click on the toolbar, a drop-down row or a search result: a command without parameters runs, one with parameters opens its form in the context panel; an entry that is coming soon is an error naming its milestone. Never opens a native file picker: file entries (open, save as, write deck) open their command's form |
 | `ui.select` | `kind` (`set`, `material`, `section`, `step`, `boundary_condition`, `load`, `reference_point`, `coupling`, `fluid_domain`), `name`; nothing to deselect | selects a definition as a browser click does; its properties (with Edit and Delete) show in the context panel |