feat: show trading paused banner and disable trading on key detail pa…

[oyeyinka1]

Closes #777

Summary

• Added an optional tradingPaused field to the key data type
• New yellow banner on the key detail page: "Trading is temporarily paused for this key" (hidden when not paused)
• Buy button is disabled with the tooltip "Trading is currently paused" while paused
• Trade dialog (Buy and Sell) is also disabled with the same tooltip while paused
• Banner and buttons return to normal when tradingPaused becomes false

Testing

• pnpm lint (0 errors; 1 existing warning in ActiveStakesList.tsx, not touched)
• pnpm build
• Added CreatorDetailPage.tradingPaused.integration.test.tsx and TradeDialog.tradingPaused.test.tsx
• Some existing tests already fail on the base code (e.g. TradeDialog.holdingCap, TradeDialog.confirmationFees fail identically without my changes). I did not touch them.

Checklist

• Linked issue or backlog item
• Scope is limited to the stated change
• Updated docs if behavior or setup changed
• Added screenshots for UI changes when relevant

[drips-wave]

@oyeyinka1 Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

Learn more about application limits