fix(core): receiver policy check before any read, smt-key tag ruling (A9), and the DSM core row sweep

[cryptskii]

DSM core batch for beta: one fix, three tests, an owner ruling on the relationship-key tag, and seventeen conformance rows re-verified. CONFORMANCE §6.51 records it.

Fix

The receiver checks the token's policy before it reads the sender's register (MR-DSM-0029, G13).

• Before: the sync prevalidated each bound pair first, walking the sender's lineage over the network. Only then did the apply check the token's committed policy, which the receiver already holds.
• Now: the sync checks the policy first. The apply keeps its own check, under the state-machine lock.

Tests

• a_transfer_its_policy_refuses_is_refused_before_the_senders_register_is_read
  • A hostile sender signs a transfer of its non-transferable token, advances its own head over it, and signs the step's receipt with its per-step EK.
  • Both halves bind at B, B's sync refuses by the policy, and no member is asked for a cell.
  • Mutation (check removed): red. B asks dsm-node-1 for a register cell of the sender.
• a_non_transferable_token_refuses_its_transfer now also drives B's canonical apply with a transfer A signed.
  • Mutation (policy check skipped for transfers to this device): red.
• a_send_to_a_device_that_is_not_a_contact_moves_nothing.

Owner ruling: DSM Amendment A9

DSM/smt-key is the canonical relationship-SMT domain tag for beta, and /v1 in the explainer was an error.

• The explainer's §26 formula and §16 example are corrected.
• The code and its golden vector are unchanged, and no key migrates.
• MR-DSM-0115 and MR-DSM-0249 go Met.
• A9, not A8, because fix(sofi): beta blockers: S14, A8/S15 settled before P15-9, and a dead cell skipped before its evidence (0241) #1082 carries A8.

Rows

• Met:
  • MR-DSM-0205, 0209, 0211, 0212, 0213, 0214 (SoFi is reachable since fix(sofi): the relay carries the bytes that hold a leg cell; the §6.39 owner rulings #1056/fix(sofi): the exercise carries the trader's balances before the trade; a lineage known invalid is Invalid (SoFi Amendments S12, S13) #1064);
  • MR-DSM-0039, 0074, 0079, 0093, 0115, 0249.
• Partial, gap restated:
  • MR-DSM-0219, 0265, 0267;
  • MR-DSM-0029: adoption and the relationship tip are still decided after the register read;
  • MR-SOFI-0311: offline is outside this round, and vault creation and SoFi legs are tested in Core only.
• Corrected: the §5A Transferable check row and MR-SOFI-0311 no longer say the recipient never checks.
• VERIFICATION_MATRIX: both policy gates are added, with their mutation controls.
• DSM core totals: 90 Met, 96 Partial, 39 Missing, 0 Violated.

Verification

• Targeted runs pass on this tree: the 13 sender_admission_tests::a_* tests, including both new legs, and the G13 test after merging fix(online): a receipt binds only when its state rules hold #1078.
• make lint: Rust fmt --check and clippy --all-targets pass. The frontend eslint step did not run locally (eslint is not installed in this worktree; the branch touches no frontend code).
• The Code map will report the rows this change moves. I repin them from CI's map in a follow-up commit on this PR.