feat: publish gate lists the staged state; a missing or unreachable remote stops before the commit (#159)

Files changed:
- CHANGES.md
- INSTALL.md
- VERSION
- instructions/publish-cycle.md
- instructions/setup-instance.md
- tools/CONTRACT.md
- tools/chemenu/commands/git_publish.py
- tools/chemenu/tests/test_git_publish.py

instructions/setup-instance.md

@@ -66,7 +66,8 @@ and ready for its first ingest.
    end state:
    - Given: `git remote add origin <url>`
    - Not given: stay local - then **every** later `tools/wikitool publish` needs a `--no-push`
-     (which also drops its branch check, see step 2).
+     (which also drops its branch check, see step 2). Without it, `publish` ends with exit 1
+     before it commits anything, because there is no remote to publish to.
 
 5. **Decision point - authoring conventions.** The distribution ships no filled-in conventions,
    only `kb/CONVENTIONS.md.template` and one `kb/<name>/COLLECTION.md.template` per collection.