Add the Claude Code and Copilot surface routes to AGENTS.md

New module repositories carry .claude/CLAUDE.md and
.github/copilot-instructions.md, so Claude Code and the Copilot surfaces
that do not read AGENTS.md natively still reach the router. Each file
holds only a route, per the agentic development standard.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Author: 2 people

.claude/CLAUDE.md

@@ -0,0 +1,2 @@
+<!-- markdownlint-disable MD041 -->
+@../AGENTS.md

.github/copilot-instructions.md

@@ -0,0 +1,2 @@
+<!-- markdownlint-disable MD041 -->
+Follow the instructions in [AGENTS.md](../AGENTS.md).