feat(hx): add hydronic heat-exchanger family

[jscott3201]

Summary

• add the hx equipment family for indirect liquid-to-liquid hydronic heat exchangers
• add HX-0001 effectiveness degradation, HX-0002 one-side flow missing, and HX-0003 unintended transfer while the isolating valve is commanded closed
• add a 12-point HX dictionary, family README, operator playbook, exact block diagrams, 47 deterministic scenarios, registry entries, and root/schema catalog updates

Design and safety decisions

• fix primary/secondary as topology identities while signed transfer is positive primary-to-secondary; the fault comparisons remain valid in heating and cooling
• keep effectiveness and reconciled heat transfer as host-derived values with denominator, fluid-property, timestamp, and side-energy-balance validation; the CXF graphs contain no unsafe Divide
• use one 900 s timer per missing-flow side so a side reversal cannot inherit elapsed time through a single OR
• require a final both-flow exchange command and a final physical isolating-valve command; upstream enables, common-header flows, duplicated side signals, and incoherent fleet aggregates are invalid bindings
• classify 0.125 effectiveness allowance, 1 L/s flow floors, and 5 kW transfer as executable/adoption-blocking placeholders rather than portable field recommendations
• add no cluster or global suppression because rule IDs are not equipment-instance scoped and no single repair reliably clears the family

Ontology and source posture

• Brick 1.4.4: exact generic Heat_Exchanger and active entering/leaving water point classes; side identity remains topology-dependent
• ASHRAE 223 public-review PPR2.1: exact HydronicHeatExchanger, paired inlet/outlet topology, and Role-Primary/Role-Secondary
• point notes pin the checked Brick and 223 artifacts and hashes; the 223 artifact is not represented as a final 2026 release
• EnergyPlus 25.1 epsilon-NTU documentation and official heating/cooling test models ground the physics; field fouling precedent is cited without importing a portable threshold

Rule	Source tier	Fault direction evidence	Threshold basis	Validation basis
HX-0001	A + C	EnergyPlus epsilon-NTU physics and Guelpa/Verda field fouling study; library comparison adaptation	0.125 NO_PORTABLE_DEFAULT; 900 s ADOPTED_TUNABLE	16 deterministic vectors; healthy EnergyPlus replay deferred
HX-0002	A + C	EnergyPlus four-port operation/flow behavior; library two-lane proof adaptation	1 L/s per side NO_PORTABLE_DEFAULT; 900 s ADOPTED_TUNABLE	17 deterministic vectors including all 8 command/flow combinations
HX-0003	A + B + C	EnergyPlus signed transfer physics and DOE FEMP HX condition-monitoring guidance; library closed-command adaptation	5% and 900 s ADOPTED_TUNABLE; 5 kW NO_PORTABLE_DEFAULT	14 deterministic vectors with positive/negative transfer

Validation

• targeted verifier: 47/47 HX scenarios pass; all three graph content IDs match their cards
• full verifier: all 137 rule directories pass
• registry lint: 137 rules OK
• SVG fitment: 138 SVGs clean
• book generation/build: 137 fault pages, 22 playbooks, 14 point dictionaries; mdBook succeeds
• simharness unit tests: 6/6 pass
• verifier Rust unit tests: 2/2 pass offline
• git diff --check: clean

Simulation boundary

The family README identifies and pins the official EnergyPlus 25.1 healthy heating and cooling paths, but this PR does not claim a completed Layer 3 campaign. No configured EnergyPlus executable is available in the local environment; an HX adapter/replay is intentionally left for the immediately following validation slice.