Remove Donations + Trades from Reader tab, add dashboard to Activity tab

[realproject7]

Changes

1. Remove Donations and Trades sections from Reader tab (Image 247)

The Donations (Received/Given) and Trades sections on the Reader tab are duplicated with the Activity tab. Remove them from the Reader tab entirely.

Reader tab after removal:

• PORTFOLIO summary (4 boxes)
• STORY TOKEN HOLDINGS (Moleskine cards)
• That's it

2. Add dashboard stats to Activity tab

Add a dashboard summary at the top of the Activity tab showing:

```
ACTIVITY STATS

┌──────────┐ ┌──────────┐ ┌──────────┐ ┌──────────┐
│ 1 │ │ 36.77 │ │ 3 │ │ 300.00 │
│ Trades │ │ PLOT │ │ Donations│ │ PLOT │
└──────────┘ └──────────┘ └──────────┘ └──────────┘
```

• Trade count + total trade amount (PLOT)
• Donation count + total donation amount (PLOT)
• Same 4-box grid style as Writer Stats and Portfolio
• Data already available from the activity feed query

Files to modify

• `src/app/profile/[address]/page.tsx` — Reader tab (remove sections) + Activity tab (add dashboard)

Branch

`task/749-reader-activity-cleanup`

Self-Verification (T3)

• Reader tab: no Donations or Trades sections
• Reader tab: only Portfolio + Story Token Holdings remain
• Activity tab: dashboard boxes at top (trades count/amount, donations count/amount)
• Activity feed items still display below the dashboard
• `npm run build` passes