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>
