Add AGENTS.md and CLAUDE.md for coding agents

Ground rules, building and testing with real BIND, where things live,
web UI rules, BIND gotchas, and the git and release workflow.
docs/development.md lists the packages its layout was missing.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CLAUDE.md

@@ -0,0 +1,8 @@
+@AGENTS.md
+
+## Claude Code specifics
+
+- End commit messages with a `Co-Authored-By:` trailer naming the model,
+  e.g. `Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>`.
+- Keep temporary scripts, extracted BIND trees, screenshots and test
+  servers' work directories in the session scratchpad, not in the repo.