UI polish pass: navigation, badges, and a new typeface

A round of interface improvements inspired by what makes dense game UIs actually readable. The goal was clarity without decoration.

The bottom tab bar now shows labels only on the active tab. Four tabs show an icon; one shows an icon and a name. It takes up less space, trains your eye to use the icons directly, and makes the active state unambiguous. A two-pixel line at the top of the active icon reinforces it.

Badge counters on inventory and chat are now pill-shaped. This is a small thing that was quietly wrong.

The side drawer gets color-coded section headers: a red left border for Combat, blue for Social, amber for Knowledge, gray for System. You stop reading section titles and start recognizing them by color.

Notifications already had a left border — it just wasn't as visible as it should have been. The color now matches the notification type precisely: rarity color for drops, gold for level-ups, red for deaths.

The font is new. We've been running on system sans-serif for body text since the start. It was fine. The Nomad typeface is better — more intentional, more consistent with the world. It's used everywhere now: all body text, labels, buttons, and headings.