remove SMS and phone number references

Pay per API call with USDC via the x402 protocol. No API key, no subscription.
Developers create an x402 client with their own signer and pass it to Commune.
We never touch private keys.

Backend:
- x402 payment middleware (402 response, verification, settlement)
- Wallet-based org auto-provisioning (findOrCreateByWallet with upsert)
- Per-endpoint pricing config (USDC on Base, Polygon, Arbitrum, Solana, etc.)
- Agent reputation service (EAS attestations on Base)
- Reputation API endpoints (GET /v1/wallet/reputation)

SDKs:
- TypeScript: wallet param accepts x402Client object
- Python: wallet param on CommuneClient + AsyncCommuneClient
- MCP: set_x402_client() for programmatic x402 setup
- Sync + async x402 HTTP clients with transparent 402 handling

Docs:
- x402 payments integration page
- Updated authentication docs with wallet auth section
- Example: x402-wallet-agent (TypeScript + Python)

Re-adds _Sms and _AsyncSms classes with send(); registers client.sms.send()
on CommuneClient and AsyncCommuneClient. SmsSendResult type was already
exported.