Implemented a full cleanup and stabilization pass for the local buyer/seller OmniClaw flow.

[Abiorh001]

Implemented a full cleanup and stabilization pass for the local buyer/seller OmniClaw flow.

What changed:

• consolidated the canonical local example into examples/local-economy/
• removed scattered root-level compose/policy files
• updated scripts/start_local_economy.sh to use the new example path and source .env
• fixed x402 seller verification/ledger recording
• fixed buyer and seller transaction history so latest entries show correctly
• fixed x402 custom-priced payments so recorded amounts match the actual settled amount
• standardized user-facing amount formatting to two decimals
• corrected Gateway balance handling by separating:
  • gateway_balance = spendable / withdrawable Circle Gateway available balance
  • gateway_onchain_balance = raw on-chain Gateway contract balance
• updated payer-side balance checks to use the actual spendable Gateway balance
• verified CLI/API flow end to end:
  • seller serve
  • unpaid 402
  • buyer pay
  • seller runtime 402 -> 200
  • correct buyer/seller ledger entries
  • seller CLI withdraw from available balance

Important bug fixed:

• we previously mixed raw on-chain Gateway balance with Circle Gateway available balance, which could make funds appear immediately withdrawable when they were not yet available
  through Circle batch settlement. That accounting model is now corrected.

Verified behavior:

• buyer pays protected seller endpoint successfully
• seller receives and records incoming settlement
• balances and transactions reflect the real settled amount
• seller can withdraw from the actually available Gateway balance

This makes the local two-sided example accurate and usable as the canonical reference flow.