fix: center project illustration in import mode picker

[Annieeeee11]

Summary

• Center the web-app · main chip in the Project import card by giving both cards the same illustration height
• Replace hardcoded 178px with --size-import-mode-illustration in tokens.css

Test plan

• Open New Project / Import modal
• Confirm Workspace and Project cards share the same illustration area height
• Confirm the Project chip is centered horizontally and vertically above the title
• Confirm Workspace dashed illustration layout is unchanged

Before

After

[codebanditssss]

clean, correct, and well-scoped. both import cards now share one illustration height via the new --size-import-mode-illustration token: the project card goes from h-[120px] to 178px with items-center so the web-app · main chip centers in an area matching the workspace card, and the workspace box stays 178px so its dashed layout is unchanged. checked a few things:

• the h-(--var) shorthand is the established pattern here, not a new style (Tailwind v4, and ConnectMobileModal uses it 16x, ReportProblemDialog 5x, etc.), so it fits the codebase.
• complete: both hardcoded 178px occurrences are replaced, no stray value left behind.
• token sits with the sibling --size-import-mode-card-min* tokens in tokens.css.

only thing i couldn't verify locally is whether the centered-chip result matches the agent-orchestrator reference we clone, but the before/after screenshots look right. approving.