Update network configuration endpoints

[prdlk]

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This issue was migrated from sonr-io/sonr2#211
Migration date: Fri Oct 3 03:17:20 PM EDT 2025

Description

Update network configuration with actual endpoints for testnet, devnet, and mainnet.

TODO Locations

Network Config (client/config/networks.go)

• Update testnet endpoints with actual values
• Update devnet endpoints with actual values
• Update mainnet endpoints when available

Requirements

1. Obtain actual RPC, gRPC, and REST endpoints for each network
2. Configure proper chain IDs
3. Add WebSocket endpoints if available
4. Document network parameters

Priority

Low - Required before public network launch