Harden Sirius adapter transaction boundaries

[KevinMehrabi]

Summary

• match the immutable Sirius contract's intermediate integer-floor order in both direct swap directions
• reject unsupported assets, malformed pool configurations, zero outputs, zero SIRS results, unsafe slippage, and inexact contract parameters
• apply slippage to the minimum SIRS minted and keep allowance reset, approval, action, and cleanup in one atomic wallet batch
• exclude Sirius token-to-token routing from the registry and swap UI
• add direct adapter tests and a focused security review

Why

The previous adapter could overquote a swap by one atomic unit, did not protect the minimum liquidity-token output with user-selected slippage, and lacked direct regression coverage for the external contract boundary.

Closes #249.

Validation

• npm run verify
• 22 test suites and 88 tests passed
• 26 focused Sirius and routing tests passed
• TypeScript, ESLint, npm's configured high-severity audit threshold, and the optimized production build passed

Release gate

Keep this pull request in draft until both direct swaps, add/remove liquidity, wallet rejection, and allowance cleanup have been rehearsed with a no-broadcast simulation or controlled test wallet.