[Follow-up] Header token price: show full USD value, not '< /bin/zsh.01'

[realproject7]

Background

After the recent token-price UX changes, the top header token price box can render very small USD values using the generic shortened formatter (< $0.01). For token pricing, that hides the actual value and makes the header less useful.

Goal

Show the full USD token price in the story page header token-price box, even when the value is below $0.01.

Scope

1. Update the header token price rendering so it does not use the shortened < $0.01 formatting for token price values.
2. Preserve a readable precision strategy for very small USD values (for example enough decimals/significant digits to expose the actual token price).
3. Keep the rest of the simplified two-line token-price box from [Follow-up] Price history chart: show live current price and simplify header token box #858 intact.

Acceptance Criteria

• The top header token-price box never shows < $0.01 for the token price.
• Small USD token prices display their actual numeric value with appropriate precision.
• The change is limited to token-price presentation and does not regress other generic USD formatting behavior unless intentionally updated.
• PR notes explain the chosen small-value formatting rule.

Notes

This is specifically for the story header token price display, where hiding sub-cent precision is misleading.