feat: Add Stellar Federation address lookup for human-readable names

[Austinaminu2]

Description

Stellar supports Federation addresses like alice*stellarx.com that resolve to G-addresses. Supporting Federation lookups in the create stream form would let users enter human-readable names instead of raw 56-character addresses.

Proposed Solution

In the recipient address field:

1. Detect Federation format (name*domain)
2. Resolve via StellarSdk.FederationServer.resolve()
3. Show the resolved G-address with the Federation name above it
4. Use the resolved G-address for the transaction

Also support reverse lookup: when displaying a stream, check if the recipient G-address has a known Federation name and display it.

Acceptance Criteria

• Recipient field accepts both G-addresses and Federation addresses
• Federation addresses are resolved via the Stellar Federation protocol
• Resolved address shown with confirmation before proceeding
• Error handling for: invalid domain, name not found, network failure
• Address book entries can store Federation names alongside G-addresses
• Stream cards show Federation names when available (with G-address on hover)