Replace 7k swap with Cetus, drop @7kprotocol/sdk-ts

[11felix]

Removes the last 7k usage (zapOutWithdraw, getSwapTransactionBlock) in favor of the existing Cetus aggregator paths, deletes sevenKSwap.ts, and drops @7kprotocol/sdk-ts (removes @flowx-finance/sdk and @bluefin-exchange/bluefin7k-aggregator-sdk from the tree with it). Adds bn.js as a direct dep — it was only installed transitively via 7k but is imported by cetusSwap.ts.

Breaking: getSwapTransactionBlock now takes a Cetus RouterDataV3 instead of a 7k QuoteResponse (consistent with getSwapQuote's rawQuote).

Verified: 58/58 tests, clean build, mainnet dry-runs of zapOutWithdraw (stSUI→USDC) and getSwapTransactionBlock (SUI→USDC) both succeed.

[jangid]

operate.md review — head c136f1d (2026-08-10). First operate pass; no prior bot review to dedup against.

Verified-safe core (checked against Cetus SDK source, not the PR text): slippage is fraction 0–1 on both sides (no bps mismatch; fe already passes slippage/100); min-out enforced (amountLimit = expectedOut × (1−slippage) → on-chain abort on shortfall); quote and swap use the same RouterDataV3 in the same PTB; zapOutWithdraw output goes to params.address, not a hardcoded recipient; @cetusprotocol/aggregator-sdk@1.5.5 + bn.js@5.2.5 are registry-resolved, no git refs; no leftover 7k imports in src/. CI green.

Advisory findings (non-blocking — no org repo currently calls the affected branch):

1. 🟡 getSwapTransactionBlock without coinIn ignores the address arg: the fastRouterSwap branch sources from the tx sender and (signer is "") disposes output to the sender — in sponsored/build-for-another-address flows output goes to the sender, not address. Return type also silently widens to TransactionObjectArgument | Transaction. Document or guard.
2. 🟡 slippage || 0.01 coerces an explicit 0 to 1% (cetusSwap.ts:77,86) — ?? intended; the zapOutWithdraw path passes slippage raw, so the class is internally inconsistent.
3. 🟡 The coinIn path now aborts on-chain if the supplied coin exceeds router.amountIn (routerSwapWithMaxAmountIn semantics); old 7k buildTx tolerated oversized coins. Worth a line in the PR body as the permanent record.
4. 🟢 sevenKGateway public-field removal is an unlisted (minor) API break; stale "via 7k Protocol" JSDoc + ~70 commented-out 7k lines in getSwapQuote; RouterDataV3 not exported from the package root so TS consumers must depend on the Cetus SDK directly to name it.

Recommend a small follow-up (fix ??, export the type, purge stale 7k docs). Approving — none of the above blocks.

[jangid]

operate.md: clean — CI green, slippage/min-out/recipient safety verified against the Cetus SDK source, deps registry-pinned. Advisory notes in the review comment (slippage-0 coercion, unconsumed no-coinIn branch semantics) — follow-up material, not blockers. Approvals: 2/2 — merge-ready.