feat(editor): MEP placement migration — Shift=cycle / mode-driven snapping

Migrate all 9 MEP kinds' placement tools onto the unified snapping model:
declare snapProfile ('item' for point-placed hvac-equipment / duct-terminal /
duct-fitting / pipe-fitting / pipe-trap; 'structural' for directional runs
duct-segment / pipe-segment / liquid-line / lineset), and replace the legacy
shiftKey-bypass reads with mode-driven isGridSnapActive / isMagneticSnapActive /
isAngleSnapActive. For runs the 45° lock becomes the cyclable 'angles' mode;
Alt stays the vertical-riser modifier (run drafting has no validity gate to
force). Port mating gated on "mode != off". Dropped stale "⇧ smooth/free" hints.

The bespoke MEP move-tool/selection (endpoint) tools stay on the legacy model —
they use setMovingNode(null) so no moving-scope context resolves yet; migrating
them needs scope-wiring first (follow-up).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

packages/nodes/src/hvac-equipment/definition.ts

@@ -20,6 +20,7 @@ export const hvacEquipmentDefinition: NodeDefinition<typeof HvacEquipmentNode> =
   schema: HvacEquipmentNode,
   category: 'utility',
   distributionRole: 'equipment',
+  snapProfile: 'item',
 
   defaults: () => ({
     object: 'node',

packages/nodes/src/hvac-equipment/tool.tsx

@@ -1,7 +1,7 @@
 'use client'
 
 import { emitter, type GridEvent, HvacEquipmentNode, useScene } from '@pascal-app/core'
-import { triggerSFX, useEditor } from '@pascal-app/editor'
+import { isGridSnapActive, isMagneticSnapActive, triggerSFX, useEditor } from '@pascal-app/editor'
 import { useViewer } from '@pascal-app/viewer'
 import { Html } from '@react-three/drei'
 import { useEffect, useMemo, useRef, useState } from 'react'
@@ -53,17 +53,18 @@ const HvacEquipmentTool = () => {
     if (!activeLevelId) return
 
     const resolve = (event: GridEvent): [number, number, number] => {
-      const step = event.nativeEvent?.shiftKey === true ? 0 : useEditor.getState().gridSnapStep
+      const step = isGridSnapActive() ? useEditor.getState().gridSnapStep : 0
       return [snap(event.localPosition[0], step), 0, snap(event.localPosition[2], step)]
     }
 
     // Grid-snap the cursor, then layer Figma-style alignment so the unit lines
-    // up with ducts, other equipment, and items as it's placed (Shift = free,
-    // no snap + no guides).
+    // up with ducts, other equipment, and items as it's placed. Grid + lines
+    // follow the active snapping mode (the contextual HUD chip — Shift cycles
+    // it); `'off'` is the no-snap bypass.
     const resolveAligned = (event: GridEvent): [number, number, number] =>
       alignDrawPoint(resolve(event), {
         applySnap: true,
-        bypass: event.nativeEvent?.shiftKey === true,
+        bypass: !isMagneticSnapActive(),
       })
 
     const onMove = (event: GridEvent) => setCursor(resolveAligned(event))
@@ -122,10 +123,6 @@ const HvacEquipmentTool = () => {
       >
         <div className="flex items-center gap-2 whitespace-nowrap rounded-full border border-border/60 bg-background/90 px-4 py-1.5 text-xs tabular-nums shadow-sm backdrop-blur">
           <span className="font-medium text-foreground">R/T rotate</span>
-          <span aria-hidden className="text-muted-foreground">
-            ·
-          </span>
-          <span className="text-muted-foreground">⇧ smooth</span>
         </div>
       </Html>
     </LevelOffsetGroup>