math: performance & quality pass

[bhousel]

A focused quality and performance pass over the @rapid-sdk/math package.

Constants

• Add WORLD_ZOOM = 16, WORLD_SIZE = 256 * 2^WORLD_ZOOM, WORLD_HALF, ANGLE_EPSILON = 1e-12
• Replace magic number 16777216 with WORLD_SIZE throughout Viewport, Tiler, and tests

Types

• Add Vec4 type alias for [number, number, number, number]
• Fix Extent.rectangle() return type to Vec4

closes #301

Overloads / scalar fast-paths

Avoids tuple allocation in hot loops:

• vecDot: scalar overload (ax, ay, bx, by)
• vecCross: scalar overload (ax, ay, bx, by)
• vecLengthSquare: scalar overloads (ax, ay) and (ax, ay, bx, by)
• geoSphericalDistance: scalar overload (lon1, lat1, lon2, lat2)
• geomLineIntersection: scalar 4-point overload; removes private _geomLineIntersection
• geomPathIntersections / geomPathHasIntersections use 4-point overload
• geomRotatePoints: precomputes trig, inlines scalar rotation
• geoSphericalClosestPoint: uses scalar geoSphericalDistance in loop
• vecProject: uses scalar vecDot in hot path

Modernization

• Replace Math.pow with ** throughout

Transform

• Constructor now accepts Partial<TransformProps>
• Snap near-zero and near-TAU rotation to 0 using ANGLE_EPSILON after numWrap

Viewport / Tiler

• Skip vecRotate when |rotation| <= ANGLE_EPSILON (epsilon-gated fast path)
• Normalize sin/cos to zero in visibleDimensions / visiblePolygon when near-zero
• Fix visibleDimensions assertion indexing and expected diagonal-rotation values

Dependencies

• Move @types/geojson to packages/math (correct ownership)