[UX] Writer dashboard: clean up royalties/earnings and fix claim button placement

[realproject7]

Problems

1. Duplicate royalties display: "Royalties: 0" under EARNINGS + separate ROYALTIES section below
2. Claim button disconnected from unclaimed amount (far right, looks lost)
3. Unclear what EARNINGS vs ROYALTIES means
4. Donations amount under EARNINGS shows excessive decimals too

Fix

1. EARNINGS = donations only (remove "Royalties: 0" sub-text)
2. ROYALTIES section: unclaimed amount + Claim button inline on same line
3. Layout: ROYALTIES ⓘ 0 WETH [Claim] — all one row
4. Truncate donation decimals in EARNINGS to 6 digits (use formatTruncated)

Files

• src/app/dashboard/writer/page.tsx
• src/components/ClaimRoyalties.tsx
• src/components/WriterTradingStats.tsx