engine: mesh.node.move moves nodes by a vector or to a point

The grabbed nodes (listed, on B-rep faces, or a sphere's) move; the nodes
within the radius follow by a falloff or harmonically; nodes stay on the
geometry as Relax Nodes moves them; the move is scaled back until no element
inverts. The reply gives the region's scaled Jacobian before and after and the
elements that got worse and better. One undo step. Toolbar entry Move Nodes
(Mesh, Improve) with its own icon.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UhhZMBTviDQxZvwnyP89fo

docs/features.md

@@ -6,7 +6,7 @@ Every entry is a toolbar button. **Ready** entries run their command; **coming s
 shown greyed with the roadmap milestone that brings them (ROADMAP.md). Scripts, the command line,
 the control channel and AI agents over MCP (docs/mcp.md) run the same commands.
 
-85 ready, 36 coming soon.
+86 ready, 36 coming soon.
 
 ## Geometry
 
@@ -55,6 +55,7 @@ the control channel and AI agents over MCP (docs/mcp.md) run the same commands.
 | Improve | Untangle — Repair inverted elements | coming soon (M6) |  |
 | Improve | Layers — Boundary padding and layers through thin walls | coming soon (M6) |  |
 | Improve | Relax Nodes — Relax the nodes inside a sphere to fix spikes and slivers; surface nodes slide on the geometry; kept as a field to apply again after a remesh | ready | `mesh.node.relax`, `mesh.node.relax.apply` |
+| Improve | Move Nodes — Drag nodes of the mesh, the nodes round them following by a falloff or harmonically, on the geometry; the original drawn as a ghost and the elements coloured by how their quality changes | ready | `mesh.node.move` |
 | Edit | Node — Add a node | ready | `mesh.node.add`, `mesh.node.remove` |
 | Edit | Element — Add an element on existing nodes | ready | `mesh.element.add`, `mesh.element.remove`, `mesh.clear` |
 | Edit | Mirror Mesh — Mirror a body's mesh across a plane, joined on the plane (mesh half a symmetric part) | ready | `mesh.mirror` |