docs: move the working agreement to AGENTS.md

The guidance in here is not Claude-specific — it is what this project is,
what it refuses to do, and the rules that are invisible from the code. Any
agent working here needs it, and AGENTS.md is the name they all look for.

CLAUDE.md stays as a pointer so Claude Code still finds it, and holds no
guidance of its own; two copies would drift and the wrong one would be read.
Every cross-reference in the source comments, docs, workflow and skills now
names AGENTS.md, and the image ignores both.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>

.github/workflows/refresh.yml

@@ -6,7 +6,7 @@ name: Refresh sources
 # any of it, it just hands CI fresher input.
 #
 # Twelve hours apart is deliberately well clear of the six-hour-per-source floor
-# in CLAUDE.md § Scraping conduct, and the runner enforces that floor itself, so
+# in AGENTS.md § Scraping conduct, and the runner enforces that floor itself, so
 # a manual dispatch on top of a scheduled run cannot double up on a wiki.
 on:
   schedule:
@@ -73,7 +73,7 @@ jobs:
       - name: Refresh
         id: refresh
         env:
-          # Identify the crawler with a contact URL, per CLAUDE.md.
+          # Identify the crawler with a contact URL, per AGENTS.md.
           REFRESH_CONTACT_URL: ${{ github.server_url }}/${{ github.repository }}
           # Passed through the environment rather than interpolated into the
           # run script, so a dispatch input cannot become shell.