results: results.xy, a quantity against the load factor, time or mode (#94)

A nodal field at a node per frame (nonlinear static displacements from
load factor 0, explicit frames, heat temperatures) or per mode, the
explicit energies and histories, history nodes, and the frequencies or
buckling load factors; capped at 100000 points with `every`; stale
results refused; `path` writes a two-column CSV. XY Plot is ready.

Co-Authored-By: Claude Opus 5.5 <[email protected]>
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.
 
-77 ready, 39 coming soon.
+78 ready, 38 coming soon.
 
 ## Geometry
 
@@ -150,7 +150,7 @@ the control channel and AI agents over MCP (docs/mcp.md) run the same commands.
 | Query | Probe — Displacement, rotation, reaction and stress at nodes, element section forces, a mode shape, or an explicit field frame (or click the model) | ready | `solve.probe`, `solve.history` |
 | Query | Reactions — Reaction force and moment sums per set | ready | `results.reactions`, `results.export.csv` |
 | Query | Free Body — Free-body forces across a cut | coming soon (M9) |  |
-| Plots | XY Plot — Plot a quantity against time or another | coming soon (M9) |  |
+| Plots | XY Plot — Plot a quantity against the load factor, time or mode | ready | `results.xy` |
 | Plots | Path Plot — Plot a quantity along a path | coming soon (M9) |  |
 | Plots | Cut — Section cuts through the model | coming soon (M9) |  |
 | Plots | Display Group — Show and hide parts of the model | coming soon (M9) |  |