Adds a "Classic icons" toggle in the structure-icons section of the
Graphics Settings modal. Off (default) keeps today's renderer look;
on switches to a classic style — lighter player-colored shape behind
a dark icon glyph, with 0.75 alpha for a subtle translucent feel.
Exposes the underlying tuning as new render-settings knobs
(`structure.fillDarken`, `borderDarken`, `iconAlpha`, `iconR/G/B`) and
threads them through the structure shader as uniforms, replacing the
previously hardcoded `darken(_, 0.65)` / `darken(_, 0.35)` calls and
the hardcoded white `vec3(1.0)` icon color. The `classicIcons` boolean
in the override schema is the single user-facing knob; the generator
derives the five underlying field values from it. Extends the
ClientGameRunner live-apply path to copy the `structure` slice too,
and adds tests covering the schema and preset derivation.
Adds a single "Name color" toggle (Colored / Black) to the Graphics
Settings modal, backed by a `darkNames` boolean in the override schema
that derives the five underlying name-rendering fields
(fill/outline player-color flags + static outline RGB). Forcing the
outline RGB to 0 in dark mode is what makes the shader's defaultFill
ramp actually render black — flipping the boolean uniforms alone
wasn't enough because the fill is derived from uOutlineColor when
fillUsePlayerColor is false.
Flips the render-settings.json defaults so black names are the
renderer baseline; the modal's no-override state follows the JSON
source of truth. Adds tests covering schema parse behavior and the
generateRenderSettings derivation for each override field.
evanpelle