[future] Plan mainnet deployment strategy

[whoabuddy]

Context

After testnet validation, plan the mainnet deployment including:

• Security audit requirements
• Migration path from KV-based agent records to on-chain identity
• CAIP-2 identifier scheme for mainnet
• Governance model for registry administration

Acceptance criteria

• Mainnet deployment plan documented
• Security considerations addressed
• Migration strategy from KV → on-chain defined
• Timeline and prerequisites listed