style: fix AI code review findings for vendor backend

_bmad-output/implementation-artifacts/sprint-status.yaml

@@ -1,5 +1,5 @@
 # Sprint Status - Entropyk
-# Last Updated: 2026-02-24
+# Last Updated: 2026-02-28
 # Project: Entropyk
 # Project Key: NOKEY
 # Tracking System: file-system
@@ -53,6 +53,10 @@ development_status:
   1-8-auxiliary-transport-components: done
   1-11-flow-junctions-flowsplitter-flowmerger: done
   1-12-boundary-conditions-flowsource-flowsink: done
+  epic-1-retrospective: optional
+
+  # Epic 2: Fluid Properties Backend
+  epic-2: done
   2-1-fluid-backend-trait-abstraction: done
   2-2-coolprop-integration-sys-crate: done
   2-3-tabular-interpolation-backend: done
@@ -61,7 +65,7 @@ development_status:
   2-6-critical-point-damping-co2-r744: done
   2-7-incompressible-fluids-support: done
   2-8-rich-thermodynamic-state-abstraction: done
-  epic-1-retrospective: optional
+  epic-2-retrospective: optional
 
   # Epic 3: System Topology (Graph)
   epic-3: done
@@ -125,7 +129,7 @@ development_status:
   epic-8-retrospective: optional
 
   # Epic 9: Coherence Corrections (Post-Audit)
-  epic-9: in-progress
+  epic-9: done
   9-1-circuitid-type-unification: done
   9-2-fluidid-type-unification: done
   9-3-expansionvalve-energy-methods: done
@@ -154,13 +158,13 @@ development_status:
   11-2-drum-recirculation-drum: done
   11-3-floodedevaporator: done
   11-4-floodedcondenser: done
-  11-5-bphxexchanger-base: in-progress
-  11-6-bphxevaporator: backlog
-  11-7-bphxcondenser: backlog
-  11-8-correlationselector: backlog
-  11-9-movingboundaryhx-zone-discretization: backlog
-  11-10-movingboundaryhx-cache-optimization: backlog
-  11-11-vendorbackend-trait: backlog
+  11-5-bphxexchanger-base: done
+  11-6-bphxevaporator: done
+  11-7-bphxcondenser: done
+  11-8-correlationselector: done
+  11-9-movingboundaryhx-zone-discretization: done
+  11-10-movingboundaryhx-cache-optimization: done
+  11-11-vendorbackend-trait: done
   11-12-copeland-parser: ready-for-dev
   11-13-swep-parser: ready-for-dev
   11-14-danfoss-parser: ready-for-dev
@@ -171,7 +175,7 @@ development_status:
   # Support for ScrewEconomizerCompressor, MCHXCondenserCoil, FloodedEvaporator
   # with proper internal state variables, CoolProp backend, and controls
   epic-12: in-progress
-  12-1-cli-internal-state-variables: ready-for-dev
+  12-1-cli-internal-state-variables: in-progress
   12-2-cli-coolprop-backend: ready-for-dev
   12-3-cli-screw-compressor-config: ready-for-dev
   12-4-cli-mchx-condenser-config: ready-for-dev