Add `StreamDetailDrawer` Stellar Expert transaction links

[ritik4ever]

Problem

Stream events in the drawer show transaction hashes as plain text. Clicking them should open the Stellar Expert explorer.

Scope

Render all transaction hashes in the event history as clickable links to https://stellar.expert/explorer/testnet/tx/<hash>.

Acceptance criteria

• All txHash values rendered as links to Stellar Expert testnet
• Links open in new tab with rel='noopener noreferrer'
• Hash displayed truncated (first 8 + last 8 chars) with full hash in tooltip
• Vitest test asserts correct href for a mock transaction hash

Complexity: Easy · 50 points

[espcris05-commits]

/attempt #399

I'd like to add StreamDetailDrawer Stellar Expert transaction links.

Wallet USDC: GCR377MUJ75YKFLNZKT6XPWNDUIEDZDUHUWY5E2LHOBBSSJDU7MJRZXF
Wallet BNB: 0x6851F2cCD4C4EA991734FAA83c027A909f2703f3