feat: bug-report collector tools/bugreport.py and instructions/bug-report.md (#157)

Files changed:
- .gitea/workflows/ci.yml
- CHANGES.md
- INSTALL.md
- VERSION
- instructions/bug-report.md
- instructions/gates.md
- instructions/setup-instance.md
- instructions/upgrade-instance.md
- reports/CONTRACT.md
- tools/README.md
- tools/bugreport.py
- tools/chemenu/tests/test_bugreport.py

tools/README.md

@@ -60,6 +60,13 @@ tools/
     tests/                 pytest suite
 ```
 
+**A script beside the package.** `bugreport.py` is not part of `chemenu` and imports nothing
+from it: it is the bug-report collector ([../instructions/bug-report.md](../instructions/bug-report.md)),
+and the case it exists for is a checkout where `wikitool` does not start. It therefore uses the
+standard library only, keeps to Python 3.8 syntax so that an old interpreter can still run it, and
+exits 0 or 1 - never 42, since it opens no gate. `dist export` ships it with the rest of `tools/`;
+its tests (`tests/test_bugreport.py`) run it on a bare interpreter (`-I -S`) to keep that promise.
+
 **Two consumers, one core.** The CLI is not the only caller any more. The cores
 (`search/service.py`, `lint_core.py`, `types_core.py`, `catalog.py`) hold what
 decides an answer and import no `typer` and no `rich`; the modules under `commands/` turn