Add Jupiter-powered token swap MVP

[GuiBibeau]

User Story

As a portfolio user, I want to swap one token for another from my portfolio so that I can rebalance without leaving the app.

Context

This is the most advanced ticket in the first batch and should land after wallet and portfolio basics are stable. The goal is an MVP swap flow powered by a Solana swap aggregator such as Jupiter.

Acceptance Criteria

• Users can select an input token and an output token
• The app fetches and displays a quote preview before submission
• The UI shows expected output and key swap details like slippage and fees
• The user can submit the transaction through their wallet
• Success, pending, and failure states are handled clearly
• The swap flow is implemented in a modular way so it can improve later

Notes

• Keep the first pass intentionally narrow and reliable
• Make risk and transaction state visible to the user
• Design the flow so it can evolve into a richer trading experience later

Out of Scope

• Advanced routing controls
• Limit orders
• Cross-chain swaps

Size

Medium