Round 7 of use case-based fixes, operator result types, IDE harness cleanup, and isolated evaluators

[KubaO]

Documentation

• The Assert pages describe a failing assertion as the IDE actually reports it, and no longer mention a Test Explorer.
• The operator pages gain result-type and promotion rules, and ten of them are corrected against the compiler.
• Data Types compares Decimal with Currency for money, and says date literals are month-first whatever the regional format.
• New troubleshooting sections cover keeping a project in Git, check_code_regions failures, and Nav-parent orphan detected.
• The welcome page and the PDF book list the four foundation tutorials.
• Event now carries its VBA-Docs attribution.
• Authoring says to paste the examples.bat summary line into a pull request that adds a code sample.

Tooling

• tbbuild and tbrun share scripts/lib/tb-ide.mjs, and a relative project path now loads.
• Every harness run puts the IDE's recent list, project state and .twinproj association back as it found them, with check_tb_registry.mjs as the self-test.
• Each test lane gets a private IDE copy inside a kill-on-close job, so a run that dies takes its IDEs with it.
• check_regex_safety prints the whole witness, gives advice that matches the docs, and exits 2 when the gate itself fails.
• check_code_regions no longer dies during a live serve.bat rebuild, and serve.bat stops leaving empty _serve-offline and _serve-pdf folders.

Use-case evaluation

• Round 7 ran 8 cases, found 19 defects, and was the first to compile and run an evaluator's deliverable.
• Evaluators now run as isolated claude -p processes through eval/run_case.mjs, because a subagent inherits CLAUDE.md and with it WIP.md.
• eval/transcript.mjs reads each evaluator's full session to check the order in which it searched, navigated and grepped.
• Round 8 is under way, with five cases run.

Maintainer notes

• WIP.HelpAddin.md plans an IDE help add-in and a harness that tests add-ins by machine.
• Six twinBASIC defects are queued in BUGS-TO-REPORT.md.