feat: stack development in three phases - stack-dev (design), stack-build, stack-close, handed over through tracker states (#168)

stack-build and stack-close carry disable-model-invocation, so each phase change is
the operator's slash command; no skill offers a mid-session /model or /effort switch.
Mode rules and the phase table move to instructions/dev/stack-mode.md, publish and CI
waiting to instructions/dev/publish-and-ci.md, the ready definition to issue-tracking.md.

Files changed:
- AGENTS.md
- CHANGES.md
- DEVELOPMENT.md
- README.md
- VERSION
- docs/model-and-effort-selection.md
- instructions/CONTRACT.md
- instructions/dev/commonplace-kb.md
- instructions/dev/dev-setup.md
- instructions/dev/doc-pull-through.md
- instructions/dev/issue-tracking.md
- instructions/dev/publish-and-ci.md
- instructions/dev/stack-build/SKILL.md
- instructions/dev/stack-close/SKILL.md
- instructions/dev/stack-dev/SKILL.md
- instructions/dev/stack-mode.md
- instructions/dev/testing-conventions.md
- instructions/dev/version-parts.md
- tools/chemenu/commands/git_publish.py
- tools/chemenu/tests/test_git_publish.py
- tools/chemenu/tests/test_instructions_cmd.py

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

AGENTS.md

@@ -335,8 +335,9 @@ see [Gates](#gates).
 
 Extending `tools/wikitool`, the type schema, or the instruction/skill layer itself (rather than
 operating on wiki content) is a different session type with different rules - see the
-`stack-dev` skill, nested under [instructions/dev/](instructions/dev/) along with the
-procedures it routes to. Setting up a clone of this origin repository for that work - the demo
+`stack-dev` skill, the entry to that work's three phases (`stack-dev`, `stack-build`,
+`stack-close`), nested under [instructions/dev/](instructions/dev/) along with the
+procedures they route to. Setting up a clone of this origin repository for that work - the demo
 corpus, the preflight, `dist export` as a build and test tool - is
 [instructions/dev/dev-setup.md](instructions/dev/dev-setup.md). Never present in a distributed
 instance.