Track terminations of Payee wallets (dApp, non-dApp)

[timfong888]

Linear Ticket: XFN-57

JTBD: When analyzing retention, I want churn metrics so I can identify and address user drop-off.

Acceptance Criteria

• Count when all rails have been terminated for a wallet
• Filter terminated wallets by dApp vs end user vs All Wallets
• Display churn trend over time

Persona: Protocol Team