feat(backends,storage,core,markdown,infra): claude agent sdk backend, session store, transcript seeding, runner isolation

src/beaver_gateway/frontends/base.py

@@ -36,7 +36,7 @@ class GatewayRuntime:
     the name in hand, so the indirection lives one step earlier.
 
     ``mcp_internal_urls`` is filled in Phase 2.1: one loopback URL per
-    declared ``McpServer`` so ``ClaudeCodeBackendAdapter`` (Phase 2.2)
+    declared ``McpServer`` so ``ClaudeSdkBackend``
     can pass them to ``BackendOptions.mcp_servers`` without re-running
     discovery.