content: four concept pages tagged guideline; the template's guideline filter is a default, not a setup question (#179)

Files changed:
- CHANGES.md
- VERSION
- kb/CONVENTIONS.md
- kb/CONVENTIONS.md.template
- kb/concepts/decisions/Diff-Reviewable Agent Edits.md
- kb/concepts/decisions/Structural Enforcement over Documented Rule.md
- kb/concepts/problems/Ambient Environment Dependency.md
- kb/concepts/problems/Green Suite Blind Spot.md
- kb/log.md

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

kb/CONVENTIONS.md.template

@@ -120,8 +120,10 @@ disagreement between sources.}
 no type or field for a guideline - which pages are guidelines is this instance's decision, and it
 is written down here and nowhere else.
 
-{The selection, as `search` predicates - for example `--tag guideline` - or "none" if this
-instance exports no guidelines.}
+**The filter is `--tag guideline`.** A page carries the tag when its content is a rule an agent
+working in another repository should follow there as it stands. This is a default, not a setup
+question: a new instance has no pages to choose from yet. Change the filter here once this
+instance decides differently - nothing else has to follow.
 
 ## Keeping this file honest