Replicate .claude/rules scaffolding from binect-js

Add the 9-file .claude/rules set (repo-identity, session-protocol,
first-session, workplan-convention, stack-and-commands, architecture,
repo-boundary, credential-routing, agents), adapted to binect-chrome:
slug, agent name, BCHROME-WP- workplan prefix, shared communication topic.
stack/architecture/repo-boundary filled with this repo's real content.

Rewrite CLAUDE.md to the @-import structure mirroring binect-js (prior
prose migrated into the rule files), retaining an inline Kaizen reference.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.claude/rules/repo-boundary.md

@@ -0,0 +1,8 @@
+## Repo boundary
+
+This repo owns **BinectChrome** (the Chrome extension) only. It does not own:
+
+- Binect REST API access / SDK logic → `binect-js` (`@binect/js`). New API coverage belongs upstream there, surfaced through the thin `src/utils/binect-api.ts` wrapper — never reimplemented here.
+- The Binect backend service itself → external (Binect).
+- State hub code → `state-hub/`.
+- Credential issuance / routing → see `credential-routing.md` (ops-warden, OpenBao, etc.).