feat: INSTALL.md is the English installation tutorial; new tutorial docs/tutorials/first-source-to-first-answer.md with a shipped sample source; README.md links it as its first-ingestion step (#191)

Files changed:
- CHANGES.md
- INSTALL.md
- README.md
- VERSION
- docs/reference/commands/types-instructions-and-docs.md
- docs/tutorials/README.md
- docs/tutorials/first-source-to-first-answer.md
- docs/tutorials/sample-source.md
- instructions/dev/doc-pull-through.md
- tools/CONTRACT.md
- tools/chemenu/commands/docs_verify.py
- tools/chemenu/install_doc.py
- tools/chemenu/tests/test_install_doc.py

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SnAJ7Z3CpVD3PRbN73QtU2

tools/chemenu/tests/test_install_doc.py

@@ -16,22 +16,22 @@ MANIFEST = prerequisites.Manifest(
 
 CURRENT = """# Installation
 
-Vorher:
+You need:
 
 <!-- wikitool:prerequisites -->
 - **Python** ≥ 3.11
 - **Git**
 <!-- /wikitool:prerequisites -->
 
-Unter Windows zusätzlich:
+On Windows, additionally:
 
 <!-- wikitool:prerequisites-windows -->
 - **PowerShell 7 (pwsh)** ≥ 7
 <!-- /wikitool:prerequisites-windows -->
 
-## Was der Agent dich fragt
+## What the agent asks you
 
-- <!-- setup-question: identity --> **Autor-Identität** - Name und E-Mail.
+- <!-- setup-question: identity --> **Author identity** - name and email.
 """
 
 SETUP = """# Set up
@@ -57,6 +57,14 @@ def test_this_repos_install_doc_names_every_setup_question():
     assert install_doc.check_setup_questions() == []
 
 
+def test_this_repos_install_doc_has_the_section_the_finding_names():
+    """A missing question is reported as missing from a named section; that
+    name is a constant, and a renamed heading would leave the finding pointing
+    at nothing."""
+    text = install_doc.install_doc_path().read_text(encoding="utf-8")
+    assert f"\n## {install_doc.QUESTIONS_SECTION}\n" in text
+
+
 def test_this_repos_setup_instruction_marks_its_questions():
     """The check compares two sets; an instruction that lost every marker would
     compare empty against empty and pass. Guard the real file's own count."""
@@ -133,10 +141,11 @@ def test_a_question_the_install_doc_does_not_name_fails(tmp_path, monkeypatch):
     issues = install_doc.check_setup_questions()
     assert len(issues) == 1
     assert "`remote`" in issues[0] and "does not name it" in issues[0]
+    assert f'§ "{install_doc.QUESTIONS_SECTION}"' in issues[0]
 
 
 def test_a_question_no_longer_asked_fails(tmp_path, monkeypatch):
-    install = CURRENT + "- <!-- setup-question: telemetry --> **Telemetrie**\n"
+    install = CURRENT + "- <!-- setup-question: telemetry --> **Telemetry**\n"
     _tree(tmp_path, monkeypatch, install=install)
     issues = install_doc.check_setup_questions()
     assert len(issues) == 1