Data: Solver with Simplex LP, integer branch and bound and a nonlinear method (#326)

data.solver maximises, minimises or targets a value in an objective cell by
changing variable cells under <=, >=, =, int and bin constraints. Simplex LP
linearises the model through recalculation, checks linearity and solves it
with a two-phase simplex; integers use branch and bound. The GRG Nonlinear
choice runs an augmented-Lagrangian projected-gradient method. The model is
saved as hidden solver_* names; Solver Parameters and Solver Results dialogs.

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

docs/gaps.md

@@ -98,8 +98,10 @@ No alpha blockers: every core workflow passes the [alpha gate](roadmap.md#alpha-
   data model (`data.fromWeb`, `data.relationships` missing). **Estimate:** 60–100 h.
 
 ### 13. Analysis tools: Solver, Analysis ToolPak, Forecast Sheet (F)
-- `data.solver`, `data.analysisToolPak`, `data.forecastSheet` missing; FORECAST.ETS family missing.
-  **Estimate:** 22–35 h.
+- `data.analysisToolPak`, `data.forecastSheet` missing; FORECAST.ETS family missing. Solver
+  (`data.solver`) has Simplex LP with integer/binary branch and bound and a local nonlinear method
+  (augmented Lagrangian, not GRG); Evolutionary, AllDifferent constraints, Solver options and
+  reports remain. **Estimate:** 16–28 h.
 
 ### 14. Page Layout view and print polish (U, F)
 - No paper view with rulers and in-place header/footer editing; web print exports only (#141, PR

docs/parity-checklist.md

@@ -4,7 +4,7 @@
 
 Each entry is an Excel ribbon or menu command (feature names only). It counts as implemented when GridCraft registers a command with the same id. This measures breadth only; the overall assessment (depth, fidelity, effort) is in [target-app-parity.md](target-app-parity.md).
 
-**Overall: 258 / 290 commands implemented (89.0%).**
+**Overall: 259 / 290 commands implemented (89.3%).**
 
 | Tab | Implemented | Total | Parity |
 |---|---|---|---|
@@ -14,7 +14,7 @@ Each entry is an Excel ribbon or menu command (feature names only). It counts as
 | Draw | 4 | 4 | 100% |
 | Page Layout | 23 | 23 | 100% |
 | Formulas | 23 | 23 | 100% |
-| Data | 20 | 28 | 71% |
+| Data | 21 | 28 | 75% |
 | Review | 9 | 18 | 50% |
 | View | 18 | 20 | 90% |
 | Automate | 3 | 3 | 100% |
@@ -240,7 +240,7 @@ Implemented:
 - `formulas.calculateNow` Calculate Now (Calculation)
 - `formulas.calculateSheet` Calculate Sheet (Calculation)
 
-## Data (20 / 28, 71%)
+## Data (21 / 28, 75%)
 
 Implemented:
 
@@ -264,6 +264,7 @@ Implemented:
 - `data.subtotal` Subtotal (Outline)
 - `data.showDetail` Show Detail (Outline)
 - `data.hideDetail` Hide Detail (Outline)
+- `data.solver` Solver (Analysis)
 
 Missing:
 
@@ -273,7 +274,6 @@ Missing:
 - `data.relationships` Relationships (Data Tools)
 - `data.forecastSheet` Forecast Sheet (Forecast)
 - `data.analyzeData` Analyze Data (Analysis)
-- `data.solver` Solver (Analysis)
 - `data.analysisToolPak` Data Analysis (Analysis)
 
 ## Review (9 / 18, 50%)

docs/target-app-parity.md

@@ -87,7 +87,7 @@ performance 8, stability 8, localization 4, hardware 2, platforms 2, ecosystem 2
 | PivotTables | 7 | ~65% | ~45% | 25–40 | Insert/Recommended, field list, three layouts, date grouping, show-values-as, refresh, XLSX round-trip. Missing: slicers, timelines, calculated fields/items, PivotCharts, value/label filters, number grouping, GETPIVOTDATA, data-model pivots. Round-trip never checked in Excel |
 | Charts and sparklines | 8 | ~50% | ~30% | 40–60 | 25 chart kinds, all 2-D. The chart model holds title, legend position, a data-labels flag, gridlines flag and axis titles; no axis scaling, trendlines, error bars, per-point formatting, chart sheets, 3-D, surface, map, Pareto. Several kinds don't survive XLSX round trip (open PRs #158, #161). [chart-parity.md](chart-parity.md) |
 | Page layout, print, PDF | 5 | ~80% | ~55% | 12–20 | Page setup, print titles, breaks, Page Break Preview, headers/footers, PDF export and printing. No true Page Layout view; the PDF writer uses only the 14 standard fonts without embedding (no CJK or other non-Latin text in PDF); web print only exports (#141, #143) |
-| What-if and analysis | 4 | ~50% | ~40% | 22–35 | Goal Seek, Scenario Manager, data tables. Missing: Solver, Analysis ToolPak, Forecast Sheet, Analyze Data |
+| What-if and analysis | 4 | ~50% | ~40% | 22–35 | Goal Seek, Scenario Manager, data tables, Solver (Simplex LP and a local nonlinear method; no Evolutionary or reports). Missing: Analysis ToolPak, Forecast Sheet, Analyze Data |
 | Get & Transform, external data, data model | 5 | ~15% | ~10% | 60–100 | Import of CSV/TSV, JSON, HTML. No Power Query editor, no From Web, database or folder sources, no connections or refresh, no relationships or data model, no external workbook links (dropped with a warning) |
 | Insert objects | 3 | ~55% | ~45% | 25–40 | Pictures, 8 shape kinds (Excel has ~170), text boxes, own icon set, ink with Ink to Shape, hyperlinks, checkboxes. Missing: SmartArt, WordArt, equations, signature line, objects, 3-D models, screenshot, pictures in cells (PR #105) |
 | Review, comments, protection, collaboration | 4 | ~55% | ~40% | 35–55 | Threaded comments, notes, spelling (system dictionary), thesaurus, sheet and workbook protection. Missing: comment navigation, Show Changes, Allow Edit Ranges, notes-to-comments conversion, accessibility checker, co-authoring, opening password-encrypted files (refused with a message since #17) |

docs/ui-parity.md

@@ -65,7 +65,7 @@ shortcut lists for Windows and Mac, then fill the gaps: 6–10 h.
 
 Format Cells, Insert Function/Formula Builder, Find and Replace, Go To and Go To Special, Sort,
 Name Manager, Data Validation, Paste Special, Conditional Formatting manager, Page Setup, Goal
-Seek, Scenario Manager and others exist. Missing or partial: Options, Solver, Data Analysis,
+Seek, Scenario Manager, Solver and others exist. Missing or partial: Options, Data Analysis,
 Forecast Sheet, Power Query editor, Insert Object, Equation editor, Protect/Allow Edit Ranges,
 Workbook Links, Accessibility checker.