Compile the documentation's own code samples; tooling fixes and WIP reorganisation.

[KubaO]

Code samples

• Added examples.bat, which builds the documentation's own twinBASIC code samples through the compiler and reports each diagnostic against the line in the page it came from.
• A sample opts in by adding check_build to its fence; 818 are marked today and the run takes about 42 seconds.
• The marker never reaches the reader — a marked fence renders to byte-identical HTML.
• Added a hidden fence for the declarations a sample assumes, so that context can sit beside it in the source without being published; it renders to nothing, and so stays out of the search index, the offline copy and the PDF.
• Completed the samples that were a declaration or two short of building, and declared the locals the VBA-derived pages left implicit.
• Qualified every Assert call with its package namespace, matching the IDE's own package reference.
• Closed an unterminated bold run in TestFixture's syntax line.

Tooling

• tbbuild now detects a compiler crash from the Debug Console rather than the status bar; it used to report a clean build on a project that took the compiler down.
• check_examples infers a sample's container from Me and from a top-level WithEvents field, and accepts slot, inherits, projname and hidden where the inference is wrong.
• Template projects under test/example-projects/ supply the types each package's samples assume; cef and webview2 are separate so each has exactly one browser type.
• wasm-graphviz 1.22.0 to 1.29.1.

Notes

• The sample gate is deliberately outside build.bat, check.bat, test.bat and CI — it needs a twinBASIC install and Windows with a private desktop. It is run by a person, the same arrangement sweep_a11y.mjs has.
• Split the engineering casebook out of WIP.md into five topic siblings, 199 KB down to 56 KB: WIP.md holds the rules, the siblings hold the reasoning.
• Added BUGS-TO-REPORT.md, a queue for bugs in twinBASIC itself, including a two-line compiler crash the sample sweep found.