Consume @sea-ai/tokens when the package ships

[kevinconka]

Context

src/index.css currently hand-rolls the full SEA.AI product token system (surface neutrals 1–5, content neutrals 1–3, primary/danger/warning signals, radius, spacing) for all three themes (DARK / LIGHT / NIGHT).

This was the right call to unblock the redesign, but it means the app will drift the moment the fleet updates a token value.

What to do

Once the shared @sea-ai/tokens npm package is published:

1. npm install @sea-ai/tokens
2. Replace the hand-rolled :root / [data-theme] blocks in src/index.css with the package import:

   @import '@sea-ai/tokens/css';

3. Delete the duplicated declarations — the CSS custom properties (--surface-neutral-*, --content-neutral-*, --surface-primary-3, etc.) are already used by name throughout the CSS modules, so no other files need to change.
4. Verify the three themes still render correctly by running the Playwright screenshot suite (node screenshot-app.cjs).

Acceptance criteria

• src/index.css contains no hand-rolled [data-theme] token blocks
• All three themes (DARK / LIGHT / NIGHT) look identical to current screenshots
• npm run build passes with no warnings