docs/ befuellt - Stack-Hintergrund fuer vier Themen, Pflegeklausel in AGENTS.md ergaenzt (4.3.1, #45)

Files changed:
- AGENTS.md
- CHANGES.md
- VERSION
- docs/ownership-and-templates.md
- docs/pipeline-rationale.md
- docs/version-model.md
- docs/why-gates-are-code.md

AGENTS.md

@@ -275,3 +275,10 @@ and `tools/README.md` are part of the change that introduced a stage, a command
 not follow-up work: nobody comes back for them, and a document that describes a repo which no
 longer exists is worse than none. The mechanical half - command tables, contracts, ignore
 canaries - is checked by `tools/wikitool docs verify`; the prose half is yours.
+
+`docs/` pages are held to a different clock than those three. A README goes stale on every new
+flag; a `docs/` page goes stale only when the reasoning it wrote down stops holding - a gate
+that stops living in code, an ownership line that moves, a boundary redrawn - which is rarer
+and not tied to any one commit. Nothing checks this by construction: a page there carries no
+normative sentence (see [File naming](#file-naming)), so there is no rule for `docs verify` to
+check, only a rationale for a session to notice has gone stale and to update or retire.