refactor: split the aura-std roster into C28 layer crates

Phase 4 of the Stratification milestone. aura-std held four C28 ladder
layers in one roster; this cuts them into layer-aligned, aura-core-only
node crates so the import direction is enforced by the crate graph:

- aura-std        — engine nodes only (arithmetic/logic/rolling + sinks)
- aura-market     — session, resample
- aura-strategy   — bias, stops, sizer, cost-model machinery
- aura-backtest   — sim_broker, position_management
- aura-vocabulary — the relocated closed std_vocabulary roster

Node modules move verbatim (byte-identical renames); consumers are
rewired by import path only. A new structural test
(aura-vocabulary/tests/c28_layering.rs) asserts each node crate's
[dependencies] stay within its C28-permitted inner set, catching the
acyclic-but-outward violation the compiler misses.

Behaviour byte-identical: full workspace suite green (1448 tests), no
golden edited, clippy -D warnings clean. C28 Status block updated.

closes #288

crates/aura-ingest/Cargo.toml

@@ -25,6 +25,9 @@ aura-engine = { path = "../aura-engine" }
 zip = "2"
 # the integration tests bootstrap a sample harness + fold a RunReport
 aura-std = { path = "../aura-std" }
+aura-market = { path = "../aura-market" }
+aura-strategy = { path = "../aura-strategy" }
+aura-backtest = { path = "../aura-backtest" }
 # chrono / chrono-tz build the Berlin-local-wall-clock window bounds + the
 # Session node's timezone for the real GER40 session-breakout example/test
 # (examples/ger40_breakout_real.rs, tests/ger40_breakout_real.rs). Pinned to

crates/aura-ingest/examples/shared/breakout_real.rs

@@ -43,7 +43,9 @@ use aura_engine::{
     join_on_ts, summarize, Composite, Edge, FlatGraph, GraphBuilder, Harness, RunManifest,
     RunReport, SourceSpec, Target,
 };
-use aura_std::{And, Delay, EqConst, Gt, Latch, Recorder, Resample, Session, SimBroker};
+use aura_backtest::SimBroker;
+use aura_market::{Resample, Session};
+use aura_std::{And, Delay, EqConst, Gt, Latch, Recorder};
 use chrono::TimeZone;
 use chrono_tz::Europe::Berlin;
 

crates/aura-ingest/tests/real_bars.rs

@@ -13,7 +13,9 @@ use aura_engine::{
     VecSource,
 };
 use aura_ingest::load_m1_window;
-use aura_std::{Bias, Recorder, SimBroker, Sma, Sub};
+use aura_backtest::SimBroker;
+use aura_std::{Recorder, Sma, Sub};
+use aura_strategy::Bias;
 use data_server::{DataServer, DEFAULT_DATA_PATH};
 
 /// Bootstrap the cycle-0007 two-sink signal-quality harness (mirrors

crates/aura-ingest/tests/streaming_seam.rs

@@ -13,7 +13,9 @@ use aura_engine::{
     Target,
 };
 use aura_ingest::{M1Field, M1FieldSource};
-use aura_std::{Bias, Recorder, SimBroker, Sma, Sub};
+use aura_backtest::SimBroker;
+use aura_std::{Recorder, Sma, Sub};
+use aura_strategy::Bias;
 use data_server::loader::CHUNK_SIZE;
 use data_server::{DataServer, DEFAULT_DATA_PATH};