Keep ProfilePill immune to inherited text casing and tracking

[kualta]

Summary

Follow-up to #18. App headers commonly set uppercase tracking-widest on the nav that wraps the account control — site's header does exactly this — and both properties inherit, so the pill would render UPPERCASE and letter-spaced in some apps and not others. That defeats the point of having one shared pill.

ProfilePill now restates the base layer's own defaults (normal-case tracking-tight) instead of accepting whatever it inherits, so it looks identical wherever it is mounted.

Note the baselines move by a hair: letter-spacing declared in em resolves against the element's own font size, while an inherited value arrives already computed at the ancestor's. Restating tracking-tight on the pill is the typographically correct one of the two.

Testing

• bun run lint and bun run typecheck clean (same pre-existing warnings as Add ProfilePill component #18).
• Baselines re-rendered through the pinned container; only the two #components snapshots changed.
• Driven in Chrome against bun run dev: with text-transform: uppercase and letter-spacing: 0.1em applied to the pill's ancestor, the pill stays none / normal and its username keeps the exact same rendered width (45.13px before and after), while a plain sibling span in the same parent inherits both (uppercase, 1.6px) — confirming the parent really was leaking and the pill now resists it.