v1.51.0 — the glossary names the landscape and the organization chart

The glossary names two pictures (#115): the landscape, Landschaft, as the picture of one system among those it runs on, takes its data from and gives data to, and the organization chart, Organigramm. The chat's opening rows went through the German pipeline for robertblust/design #286, and the editor, reading the German alone, stopped at both: it would have written Systemlandschaft, and it met Organigramm with no row to hold it to. The rows keep the widget's own caption for the first and fix the second, so the next translation does not reopen either. The reusable check's marker and the AGENTS.md header name v1.51.0 (#116).

What breaks. Nothing.

How to take it. conventions.json to v1.51.0, the workflow reference check.yml@v1.51.0, and sh conventions/conventions-sync sync. No family resync; each member in its own re-pin.

Verified: sh test/run.sh, conventions-check and conventions-format pass on the release commit.