feat(client): add 16 P2 tests — camera, entity alpha/color, UI (#492)
gdUnit4 tests covering:
- Camera (5): zoom default, smoothing convergence, viewport tracking,
follow movement, no-panning lock per D-014
- Entity alpha/color (4): null visibility default, peripheral/forward
transition, terrain object color, player color constant
- UI (7): monologue visible/hidden, interaction verbs, inventory grid,
dialogue overlay, pause indicator, fog blob count, fog z_index
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>