fix(web): resize the floating preview from any edge - #10467

Eligibility
The change adds eight production resize interaction paths, derives the preview frame from viewport aspect ratio, and replaces the fixed initial 320x200 layout with a dynamic default. It also changes the live mini-player state model, so the visible behavior spans interaction handling, layout calculations, browser-surface sizing, and state management.

Notes:
No code owners found in target merge base 6abdf37

Correctness (unavailable)
Monthly spending limit reached (workspace setting).