feat: integrate canonical Deepstate settlement on Robinhood Chain

[dangerousfood]

Summary

Adds a production-scoped Deepstate action to 0x Settler on Robinhood Chain.

• expose DEEPSTATE only through RobinHoodMixin
• pin the canonical engine at 0x6cf19308C22FC82ea620Fa0B3E94948d20f27B96
• require the pinned engine to contain code when production Settlers are deployed
• use the standard SettlerSwapAbstract action-mixin architecture
• use 0x ppm funding and the signed buy token, recipient, and final slippage check
• require every fill to use the declared direct market and direction with sorted token addresses
• force every fill to noRest
• restrict the engine from generic BASIC calls so validated execution cannot be bypassed
• cap ERC-20 authority with an exact temporary approval and clear it after settlement
• reject non-exact input accounting, including fee-on-transfer and rebasing behavior
• refund only selected but unmatched input while retaining unselected input for later actions
• support ERC-20 and native input/output without forwarding unrelated native balance
• keep the action unavailable on non-Robinhood Settlers

Verification

• Deepstate unit suite: 16/16 passed
• bounded ERC-20 spend fuzzing: 100,000 runs passed
• live Robinhood fork at block 48,052,050: passed against the deployed engine
  • real resting maker order created and consumed
  • live 10 bps protocol fee verified
  • unmatched input refunded
  • taker remainder did not rest
  • no Settler token residue
  • temporary allowance cleared
• broader default-profile unit/FV/invariant coverage: 190 tests passed
• SafeGuard suite under its required London profile: 20/20 passed
• Uniswap V4 invariant: 20,000 calls with zero reverts
• production builds: passed
• VIP/action selector collision check: passed
• scoped Foundry lint, formatting, and diff checks: passed
• existing gas snapshot comparison: no regressions

Gas Optimization

• Deepstate execution gas snapshot: 205,054 gas
• RobinHoodSettler runtime size: 22,928 bytes, leaving 1,648 bytes below EIP-170
• RobinHoodSettlerIntent runtime size: 20,456 bytes, leaving 4,120 bytes below EIP-170
• RobinHoodSettlerMetaTxn runtime size: 19,649 bytes, leaving 4,927 bytes below EIP-170
• action calldata reuses the signed transaction recipient and buy token rather than encoding duplicates

Upstream base

Based on 0xProject/0x-settler@1df90874.

[dangerousfood]

Review has moved upstream to 0xProject#640: 0xProject#640