Star-cruise: exit button + drag/pinch/WASD nav + 512x384 res (sw v6)

Fixes from live feedback:

EXIT — an always-visible ✕ button (z-60, thumb target, safe-area) + Escape + the 🛸 toggle — the overlay can no longer trap you; torn down on stop().

NAV — hand-rolled orbit/dolly/pan (no new Three addon). Mouse drag = look, wheel = zoom; touch drag = look, two-finger pinch = zoom; WASD/arrows fly.

RESOLUTION — internal target now aspect-fit, DPR/mobile-aware, capped long edge 512 (fine) / 448 (touch) — 512x384 on desktop; still dithered/crunchy PS1.

• so the deploy lands on reload.

Verified: test/starcruise-run.js 37/37 PASS (adds EXIT-click-stops-mode + 512x384 assertions; core band-plays-on-beat + clean-teardown preserved).

▶ Play it: Mercury Interrogation — where the harmony organ has the least anywhere to hide https://stellate.app/?genre=bebop&seed=6241&path=694.13834,713.13867,675.13867&xdur=13.122

58c9d4e https://github.com/aboard-io/stellate/commit/58c9d4e12231d7451607819b139ea5f4cdd91a35