Expand native web compatibility and add preflight

[lucamykael]

Summary

• compile Mendix 11 layouts, snippets, menus, broader built-in/form widgets and schema-backed pluggable widgets through native React contracts
• compile graph nanoflows, client/server actions and the matching Runtime operation catalog
• add a read-only mxrb preflight command that audits the renderer actually selected for Mendix 6/7/9/11
• fix widget package roots and React 19 findDOMNode compatibility
• run a public Sudoku MPR acceptance project pinned by commit in CI

Validation

• CI-equivalent with public Sudoku fixture: 882 examples, 0 failures; 98.61% lines and 95.15% branches (gates: 98%/95%)
• local four-project acceptance matrix: 99.52% lines and 96.56% branches
• bundle exec rubocop: 222 files, 0 offenses
• clean preflight: LearnNow, MyFirstModule, SLATaskApp, Sudoku and VetClinic
• native Rspack: SLA 66 files, Sudoku 566 files, VetClinic 430 files; all support manifests empty
• official mx check: SLA and Sudoku 0 errors
• official MxBuild 11.12.1: SLA and Sudoku BUILD SUCCEEDED

Explicit boundary

Legacy Mendix 6/7/9 builds still use the Dojo renderer, where only Data Grid 1 is compiled. The new preflight reports those unsupported legacy widgets accurately instead of auditing them through the Mendix 11 React path. Mendix 5/8/10 remain fail-closed without audited seeds.

The prior absolute 100% coverage default remains available locally. CI uses separate 98% line and 95% branch floors plus the pinned real-project acceptance run; private Team Server credentials are not required.