feat: wikitool upstream merge/verify - code procedure for taking a stack update (4.5.0-beta.1, #30)

Files changed:
- AGENTS.md
- CHANGES.md
- VERSION
- instructions/gates.md
- instructions/private-instance.md
- tools/CONTRACT.md
- tools/README.md
- tools/chemenu/cli.py
- tools/chemenu/commands/dist_cmd.py
- tools/chemenu/commands/run_budget.py
- tools/chemenu/commands/upstream_cmd.py
- tools/chemenu/ownership.py
- tools/chemenu/tests/test_upstream_cmd.py

tools/README.md

@@ -43,6 +43,7 @@ tools/
     links.py               labelled edges in `related:` - the graph's semantics as data, not prose
     kb_collections.py      collection discovery (a directory with COLLECTION.md), and what one declares about itself
     conventions.py         kb/CONVENTIONS.md: what this instance decided about authoring, as opposed to what the stack enforces
+    ownership.py           the stack-vs-instance boundary under a content stage - one predicate, read by `dist_cmd.py` and `commands/upstream_cmd.py` so the two cannot answer it differently
     type_resolver.py       type-spec loading and schema resolution
     lint_core.py           the lint checks and the report, with no CLI attached
     types_core.py          type-spec listing/description, with no CLI attached