Add remote subscription support so spokes can consume streaming operations
over pubsub transports (WebSocket, Redis). Extract checkAccess to access.ts
to break circular dep between call.ts and subscribe.ts.
Extracted from alkhub_ts packages/core/operations/ and packages/core/mcp/.
- Runtime-agnostic (injected fs/env deps, no Deno globals)
- Direct @logtape/logtape import instead of logger wrapper
- PendingRequestMap with pubsub-wired call protocol
- Peer-dep isolation for MCP adapter (sub-path export)
- Schema const naming convention (XSchema + X type alias)
- 68 tests passing, build + lint + test all green