Add `packages/server-v2`, a minimal Fastify server bootstrapped through the
`agent-core-v2` DI engine (`bootstrap()` -> Core `Scope`), speaking the same
`/api/v1` interface as the v1 server. Route handlers resolve Core services
via `core.accessor.get(IXxx)`.
- Serve healthz, meta, auth, oauth (login poll/start/cancel/logout) and
shutdown with the standard `{code, msg, data, request_id}` envelope.
- Re-point root `pnpm dev:server` to server-v2 and add a `src/main.ts`
foreground entry.
- Add `build/hash-imports-loader.mjs` so tsx resolves `agent-core-v2`'s `#/`
array-fallback subpath imports.
- `agent-core-v2` Phase 0 fixes so it compiles and boots: add the `event`
domain (`IEventService`), fix `gateway` `event.subscribe` -> `event.on`, fix
the `wireRecord` fallback `BlobStoreService` construction, export the
`provider` barrel, and fix a `tooldedup` test import casing.
