fix(editor): point compass needle at true north, not camera

[wass08]

Problem

The compass needle in the viewer pointed in the direction the camera was facing instead of at true north — as you orbited, the needle swung with the camera rather than staying pinned to a fixed world direction.

Cause

The needle rotation was -floorplanUserRotationDeg. The 2D/3D views are kept in sync via floorplanUserRotationDeg = cameraAzimuth − 90°, and working through the projection math (three.js spherical θ → screen, and the SVG rotate() for the 2D case) true north lands at +floorplanUserRotationDeg. The negated sign made the needle rotate opposite to north.

The formula was originally written for the 2D-floorplan-only compass and reused verbatim when the compass was portaled into the 3D viewer, so both FloorplanCompassButton instances carried the flipped sign.

Fix

Drop the negation on both compass instances (3D-viewer portal + 2D-floorplan fallback):

- northRotationDeg={-floorplanUserRotationDeg}
+ northRotationDeg={floorplanUserRotationDeg}

"Align to north" is unaffected (resets userRotation → 0 → needle up).

Testing

Verified manually against the community server — orbiting the camera now keeps the red needle pinned to a fixed world direction.

Note: for buildings with a non-zero rotation the 2D floorplan de-rotates the building while the 3D view shows true world angle, so the two branches strictly diverge by buildingRotationDeg. This PR keeps the minimal sign-flip (correct for the common axis-aligned case).

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Project	Status	Preview	Updated (UTC)
pascal	🔴 Failed	–	Jun 18, 2026, 1:25 PM

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