World-space rendering: geometry cached once, zoom pays only rasterization

Fixes the zoom frame-rate collapse and rebuilds draw() around a single
camera transform, per the user's Obsidian-style sizing proposal.

Bug fix first: the eased zoom leaked a queued rAF callback per frame --
advanceZoom applies each step through d3-zoom, whose zoom event called
markDirty() from inside the tick loop, scheduling an extra draw while the
loop scheduled its own. Draws multiplied per displayed frame; sustained
wheel ran at ~20fps against a 120Hz display. markDirty now skips
scheduling while inTick (verified: 62 frames/500ms during a 28x zoom
burst, matching pan).

World-space model: every draw call now runs in graph coordinates under
one setTransform(k). Sizes are defined as screen-px-at-fit and converted
once per geometry build (/ kFit), so nodes, node labels, arrowheads and
the hover halo scale with the graph as you zoom (0.25x painted area at
half zoom, exactly k^2) while edge widths and hull borders stay
viewer-relative hairlines (/ k). Cluster hull geometry (convex hull +
three offset fills + solid boundary -- dashes dropped for now) is built
as cached Path2Ds per data/visibility/settings change; camera moves do
zero geometry math, making zoom per-frame cost identical to pan. Label
wrapping runs once per build, not per frame. Region labels stay
viewer-relative (18px at any zoom) as UI chrome. Picking radius scales
with the world-sized discs.

Glide feel: ZOOM_EASE_MS 120 -> 45, convergence 0.1% -> 0.2%; a notch now
settles in ~260ms instead of ~750ms. Resize still paints synchronously.

Also fixes barrel-law lint violations from the settings wave (import
from @/src/core and @/src/server, not deep module paths).

src/core/index.ts

@@ -17,6 +17,7 @@
 
 export * from "./contracts.ts";
 export * from "./ports.ts";
+export * from "./render-settings.ts";
 
 export * from "./question-core.ts";
 export * from "./clusters.ts";