Moves Slot Machine into the sidebar's account section (alongside RZ
Shop/Settings/Log out) instead of being reachable only from the shop -
removes the shop's promo banner and the screen's "Back to Shop" link
accordingly.
Also closes a chunk of the visual gap against the mockup: a proper
cabinet-style panel (arched top corners, glowing border), a light
"screen" panel holding a real 3x3 reel grid instead of 3 single icons,
a decorative lever, an "RZ" marquee, and the cost/spin/auto-spin
controls each in their own bordered box. Added two new vendored icons
(gem, flask-conical) for reel variety and reward-list icons.
