Hyperspace tunnel cross-pivot transition

> **Skills:** GLSL · Three.js camera math · motion synchronization
> **Time:** ~12 hours
> **Good for:** Cinematic effects engineers · Star Wars trailer-tribute makers
> **Difficulty:** Advanced

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## Context

When the user changes selection (cross-pivot), the current visual is a
horizontal accent-streak overlay (`HyperspaceOverlay.tsx`). Star Wars canon's
hyperspace transition is much more iconic: the camera punches forward, stars
elongate into streaks converging at infinity, then resolve back into the
destination.

## Goal

Replace the current 2D streak overlay with an actual 3D hyperspace tunnel:
camera pushes forward, all visible stars elongate radially from the camera
center over ~700ms, hold the tunnel for ~200ms, then decompress back to point
stars at the destination.

## Where to start

- New `components/galaxy/HyperspaceTunnel.tsx` — R3F overlay that hijacks the
camera briefly during cross-pivot. Sample existing star positions, project
velocity vectors radially from camera, render with a custom shader that
trails them.
- `components/explorer/HyperspaceOverlay.tsx` — currently 2D; either replace
or compose with the new 3D tunnel
- Coordinate with `SceneController` in `GalaxyCanvas.tsx` so the camera dolly
syncs with the tunnel duration

## Acceptance criteria

- Cross-pivot now feels canonical rather than cosmetic
- Reduced motion: existing 80ms cross-fade preserved
- Works in galaxy view; timeline / lineage views can keep their current
transitions
- No motion sickness for users (no aggressive yaw/roll)

## Lore reference

https://starwars.fandom.com/wiki/Hyperspace