feat: recolour art and text at runtime from a named palette

[oglassdev]

A UI could only change colour by swapping whole sprites: a "warning" state needed its own copy of every piece of art, and text colour was fixed at build time. Now art and text can take a colour from a small named palette that the server picks at runtime, so one set of art serves every state.

const tone = tint("tone", { ok: "#3ddc84", warn: "#ffb020", danger: "#ff4d4d" });

<Box frame="pill" tint={tone}>
  <Text color={tone}>Wave incoming</Text>
</Box>

hud.tone(StatusHud.Tone.DANGER)

• tint(id, palette) declares a handle with a fixed palette. tint on a <Box> or <Case> frame and on <Image> takes the handle or a literal hex; color on text takes the handle.
• Tinted art multiplies the art's pixels by the palette colour, so white art shows the colour exactly and shaded art keeps its shading.
• The Kotlin binding is an enum nested in the view, one constant per palette entry. The first entry is the initial colour.
• Previews take [tone, "danger"] as state and draw the chosen entry; the default is the first entry.
• A literal hex tint is baked at build time and costs nothing at runtime.

Cost: each tinted piece of art becomes its own font glyph instead of joining the static background glyph. In shader-placed HUDs each tinted segment also uses one marker colour per palette entry.

A shader-placed HUD that needs more than 65,535 marker colours fails the build with a message.

The example adds a /tone command that tints the wave hint HUD and a status lamp in the shop.

Checked in a real 26.2 client: the HUD pill's rim, fill and text and the shop lamp show the exact palette colours and multiply products in all three tones, and the previews of the HUD match the client pixel for pixel in each tone. That comparison found the preview's HUD text shadow one step dark in some colours; previews now round it as the shader does, which applies to every shader-placed HUD preview.

Not included:

• tint on a window, HUD root, section or collection frame.
• Tints on indexed handles.
• Arbitrary runtime RGB (Tint from an arbitrary runtime RGB color, not only a fixed palette #97).

Not checked against a client: tinted runtime sprite slots (<Image bind tint>) and previews of tinted non-shader HUDs.

Closes #91. Closes #92.

Checks: just test-rust -p window-core, just gradle :runtime:test --rerun, just check-ts, just test-ts, just golden, just lint, just fmt-check.

Stacked on #104.

🤖 Generated with Claude Code