Add Valve and Damper base specs with valve/actuator enums

[agarnhart]

Summary

Add foundational equipment specs and enum types for valve and actuator modeling in the ph library. This introduces abstract base specs for Valve and Damper, updates Actuator with new classification slots, and defines 7 new Enum types (42 values total).

Equipment Specs

• Valve: abstract base for all valve equipment (actuated and non-actuated) with slots for valveFunction, valvePorts, valveBodyType, pipeFluid, and pipeSection
• Damper: abstract base for all damper equipment with ductSection slot
• ValveActuator: updated to Actuator & Valve intersection — inherits both actuator and valve slots
• DamperActuator: updated to Actuator & Damper intersection — inherits both actuator and damper slots
• Actuator: gains four new optional slots for fail position, direction, control action, and mechanism

Enum Types

All classifications use Enum rather than Choice to avoid adding new global marker tags to PhEntity.

Enum	Values	Purpose
ValveFunction	13	Piping role (isolation, control, mixing, bypass, check, …)
ValveBodyType	6	Body construction (globe, butterfly, ball, gate, plug, needle)
ValvePorts	3	Port configuration (twoWay, threeWay, fourWay)
ActuatorFailPosition	4	Fail-safe mode (failOpen, failClosed, failInPlace, failToPosition)
ActuatorDirection	2	Signal mapping (directActing, reverseActing)
ActuatorControlAction	3	Control mode (modulating, twoPosition, floating)
ActuatorMechanism	4	Drive type (electricMotor, pneumatic, hydraulic, solenoid)

Design Rationale

• Valve/Actuator separation: Non-actuated valves (manual isolation, check, PRV, TMV) are common on mechanical schedules but have no representation in Haystack today. The Valve abstract base gives them a home without requiring actuator metadata.
• Intersection types: ValveActuator : Actuator & Valve composes both concerns cleanly — valve body identity from Valve, control metadata from Actuator.
• Enum over Choice: These classifications are descriptive attributes, not functional tags needed for point/equip queries. Using Enum avoids adding 42 new global markers while still providing validated, closed-set values. If any are later deemed important enough for tag-based queries, they can be promoted to Choice.
• Damper parity: Damper follows the same pattern as Valve so that DamperActuator gains symmetry and future damper-specific slots have a home.

Files Changed

• src/xeto/ph/enums.xeto — 7 new Enum types in alphabetical order
• src/xeto/ph/equip.xeto — Valve, Damper abstract bases; updated Actuator, ValveActuator, DamperActuator