Add Stellar Anchors directory integration

[Nanle-code]

Description

Integrate with Stellar Anchors directory for fiat on/off ramps and SEP compliance.

Requirements

• Display available anchors
• Check anchor capabilities
• Link to anchor services
• SEP-1 metadata parsing
• Rating and reviews system
• Integration with asset discovery

Acceptance Criteria

• Directory loads correctly
• Anchor capabilities are shown
• SEP metadata is parsed
• Links are functional