fix(gateway): only the kernel's operator may create a shared batch on it (N55)

[LamaSu]

N55: only a kernel's operator may create a shared batch on it

The hole (live on master 7d688ce). POST /api/batches/shared checked no identity. Any authenticated key could publish a priced shared batch (slots and price per slot) under another operator's kernel. Buyers claiming its slots would believe that operator made the offer.

The fix is the kernel-operator check from routes/lob.ts and routes/carrier.ts:

• No caller (req.operatorId ?? req.userId, trimmed): 401 unauthenticated.
• Unknown kernel: 404 kernel_not_found (502 kernel_lookup_failed if the lookup itself fails).
• A kernel with no operator, or the zero address: 403 kernel_unowned.
• A caller who isn't the kernel's operator (compared case-insensitively): 403 not_kernel_operator.

Tests: shared-batch-owner.test.ts, 8 tests. 5 fail on master: the stranger, unknown-kernel, zero-operator, no-identity and blank-identity cases all got 200. Gateway tsc is clean. The full gateway suite has 3714 passed, 13 skipped and 1 failure, in negotiation-settlement-correctness.test.ts. That test passes alone 3 times out of 3, both with this change and with master's batches.ts, so it's a full-run flake and not this change.

Merge order: this is an ownership guard, so it merges after WP-A (#326) under rule 6. #375 (N49) rewrites the same file, so whichever merges second takes a small rebase. Both PRs are refvertical's.

Callers: the dashboard's BatchBoardPage creates shared batches with the signed-in user's key. After this change only the kernel's operator can create one on that kernel, which is the intent.

Board row N55 (refvertical).

🤖 Generated with Claude Code

https://claude.ai/code/session_01KBTXKQ2uqtcrsUtPnQdtf8

[LamaSu]

Closing this in favour of #403 (readmodels), by agreement with the steward (bus #5435/#5438) and readmodels (#5227/#5436).

The cross-family review of this PR found the route check fails closed, but the identity it trusts (req.operatorId) can be self-provisioned: public POST /api/auth/provision mints a key for any wallet address without a SIWE proof. #403 gates the same POST /api/batches/shared on WP-A's SIWE-proven wallet (precheckJobRead / kernelScopeOf), and also gates the claim, slots and release routes. So board row N55 is covered by #403, which merges after WP-A (#326).

🤖 Generated with Claude Code

https://claude.ai/code/session_01KBTXKQ2uqtcrsUtPnQdtf8