Regenerate agent instruction files for dev-hub MCP name

Session-protocol and related rules synced from state-hub template refresh.

CLAUDE.md

@@ -0,0 +1,12 @@
+# hub-core — Claude Code Instructions
+
+@SCOPE.md
+@.claude/rules/repo-identity.md
+@.claude/rules/session-protocol.md
+@.claude/rules/first-session.md
+@.claude/rules/workplan-convention.md
+@.claude/rules/stack-and-commands.md
+@.claude/rules/architecture.md
+@.claude/rules/repo-boundary.md
+@.claude/rules/credential-routing.md
+@.claude/rules/agents.md