Adds Tailwind typography tokens (display, headline, title, body, label, codeline),
a `.kicker` utility, and font-feature ligatures. Caps prose line length on docs.

Fixes home page rendering with system fallback fonts: next/font variable was
scoped inside a wrapping div, so `var(--font-sans)` on body resolved to undefined.
Now defines font CSS variables on `:root` via styled-jsx in _app.tsx so the body
inherits them through the cascade.

…fy chrome

Fixes home layout regressions and adds motion to the hero background.

Layout: replace `container mx-auto px-4` with `mx-auto max-w-6xl px-4 sm:px-6`
across all home sections so widths match Hero. Drop `mx-auto` from HowItWorks
and Contrast headers so kickers left-align with the grids below them.

Prose width: scope the docs `max-width: 72ch / 60ch` rules to
`main:not(.layout-full)` so the home page (`<main class="layout-full">`) is
exempt. The home `<ol>`/`<ul>`/`<h2>` were being clamped, which is what made
the timeline and capabilities pointers visually misaligned.

Motion: new `GridPulses` component renders 6 Hi-Vis Yellow pulses traveling
along the 56px grid lines behind the hero. Mixed axes/directions, gradient
heads, mild glow, snapped to lane offsets. Inherits the same radial mask as
the grid pattern so pulses fade at edges. `prefers-reduced-motion` respected
via the existing global MotionConfig.

Chrome: drop the `oss` badge from the navbar wordmark and the
"Apache 2.0 · © 2025 GoodRx OSS" line from the footer. Simpler wordmark.

Long-form docs prose was reading anonymous in Inter. IBM Plex Sans gives
the engineered DNA expected by devs and platform engineers without losing
neutrality, and pairs naturally with the existing JetBrains Mono code
font. Scoped to docs only via main:not(.layout-full) so the home page,
nav, sidebar, and TOC stay on Inter and the brand layer is preserved.

Also adds the reading hierarchy that was missing: 17px body / 1.7 line-
height, tighter heading tracking, weight ladder (h1 700, h2-h4 600),
text-wrap pretty/balance, tabular numerals on tables, and softer inline
code chips. Wordmark in nav and footer is now JetBrains Mono uppercase
with letter-spacing for a coded, set-in-stone feel.

Previously /docs returned 500 because no index page existed; the only
way to land in the docs was the deep link /docs/what-is-lifecycle.
With output: 'export', runtime rewrites/redirects aren't available, so
this uses an MDX file at /docs that imports and renders the existing
what-is-lifecycle.mdx as a component. Single source of truth, both URLs
remain valid (canonical /docs, alias /docs/what-is-lifecycle), TOC
builds correctly on both. Footer 'Docs' link points at the canonical.

Inter was carrying brand and chrome while IBM Plex Sans was scoped to
docs prose. That made three fonts on the page (Inter, Plex, JetBrains
Mono), which directly contradicted the "no third font" rule the system
was designed around. Plex reads as engineered without losing neutrality,
so it can carry the brand and chrome layers as well, restoring the
two-face commitment.

Drops the Inter import and the --font-docs variable; --font-sans now
resolves to IBM Plex Sans across every surface. The docs-scoped CSS
keeps its reading scale (1.0625rem / 1.7 / -0.005em, headings 700/600
with tighter tracking) but no longer needs to override font-family,
since Plex is global.