Add rBroker + wBroker pool, BrokerPayload, NamasteCore trait stub

- src/brokers/: pool manager, r_broker (rec.read), w_broker (rec.write),
  BrokerPayload struct, BrokerError type
- src/core/: NamasteCore trait — fetch/write/update/delete interface, stubs
- IPL step 6: spawns rBroker + wBroker pools after exchange declaration
- tests/broker_pool_test.rs: integration tests for pool spawn (skip if broker down)
- BrokerPayload unit tests + doctest in payload.rs
- Added futures-lite, serde_json to Cargo.toml
- README.md, CLAUDE.md, wiki updated to reflect new structure and status

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

README.md

@@ -87,6 +87,14 @@ rustybeds/
 │   ├── config/
 │   │   ├── mod.rs              # Loader — load() and load_from() for testability
 │   │   └── structs.rs          # Typed config structs (serde Deserialize)
+│   ├── brokers/
+│   │   ├── mod.rs              # Pool manager — spawn_r/w_broker_pool()
+│   │   ├── error.rs            # BrokerError type
+│   │   ├── payload.rs          # BrokerPayload — AMQP message body struct
+│   │   ├── r_broker.rs         # rBroker task — rec.read consume loop
+│   │   └── w_broker.rs         # wBroker task — rec.write consume loop
+│   ├── core/
+│   │   └── mod.rs              # NamasteCore trait — unified CRUD interface (stub)
 │   ├── services/
 │   │   ├── mod.rs              # Groups external service transport modules
 │   │   ├── amqp/
@@ -109,6 +117,7 @@ rustybeds/
 │   ├── example_rec.toml        # Canonical self-documenting REC template
 │   └── mst_logger_rec.toml     # Logger collection template (msLogs)
 ├── tests/
+│   ├── broker_pool_test.rs     # rBroker + wBroker pool integration tests
 │   ├── common/mod.rs           # Shared test helpers — load_test_config()
 │   └── fixtures/
 │       └── beds_test.toml      # Canonical test config fixture
@@ -149,12 +158,13 @@ The `config` crate deep-merges these at startup. Only keys present in the env fi
 | Unit test scaffolding + config fixture pattern | Done |
 | MongoDB reachability validation | Done |
 | MariaDB reachability validation | Done |
-| Broker pool (Tokio tasks) + queue declaration | Next |
-| AMQP publish / consume | Planned |
-| Broker pool (Tokio tasks) | Planned |
-| NamasteCore trait | Planned |
+| rBroker pool (Tokio tasks, queue declare, consume loop) | Done |
+| wBroker pool (Tokio tasks, queue declare, consume loop) | Done |
+| BrokerPayload — AMQP message body struct | Done |
+| NamasteCore trait (stub) | Done |
+| Factory dispatch | Next |
 | Database adapters (MariaDB, MongoDB) | Planned |
-| Factory dispatch | Planned |
+| AMQP publish / consume (full round-trip) | Planned |
 | AI database object generation | Phase 2 |
 
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