Limit CLAUDE.md to translations and verifying UI work

The file was added without being asked for. It stays, but with its scope
stated at the top so it does not grow into a second contributor guide:
the nine catalogues and what it takes to confirm a visible change works,
and nothing else.

CLAUDE.md

@@ -1,7 +1,12 @@
 # Notes for Claude
 
-Things that are true of this repository and cost somebody a round trip to
-find out. Not a style guide — `CONTRIBUTING.md` is that.
+**Scope: translations and verifying UI work. Nothing else.**
+
+This file covers exactly two things — the nine translation catalogues, and
+what it takes to confirm a visible change actually works. Do not add sections
+for anything else: no build, deploy, architecture, style or workflow notes,
+however useful they seem. `CONTRIBUTING.md` is the style guide, and everything
+else belongs in the code, the docs, or a commit message.
 
 ## Translations