Solve: how to tell if a wallet is from a dApp vs end user

## Problem

We want to measure dApp growth and wallets appear to be the most useful way because it indicates intent to pay for service. But we cannot tell the difference between a dApp wallet and a dApp's end user.

## Context

This is a critical blocker for measuring the **1000 dApps by EOY 2026** OKR.

### Current Limitation
No on-chain distinction exists between dApp and end-user wallets.

### Proposed Solutions

## Acceptance Criteria
- [ ] Design decision documented on approach
- [ ] Implementation plan created
- [ ] Ability to distinguish dApp wallets from end-user wallets in the system

## Persona
Protocol Team

## Priority
Urgent - blocks OKR tracking #65

## Linear Reference
Linked from [XFN-33](https://linear.app/filoz/issue/XFN-33/solve-how-to-tell-if-a-wallet-is-from-a-dapp-vs-end-user)