op-devstack: abstract SupernodeTestControl and add lokahi to the acceptance matrix

The devstack supernode test surface is bound to the Go implementation (`SupernodeTestControl.InteropActivity()` returns an in-process `*interop.Interop`). Abstract the `stack`/`dsl` types so the existing `op-acceptance-tests/tests/supernode/**` shapes run against either op-supernode or lokahi; complete the lokahi admin/test RPC surface the DSL needs; add lokahi to the acceptance matrix; SafeDB parity path (existing `safeheaddb_*` suites + `VerifySafeHeadDatabaseMatches` cross-node DSL, incl. the SafeDB-path env plumb for kona/lokahi and removing the one `SkipOnKonaNode`). Gate: kona-node acceptance gate stays green (shared DSL edits).

Depends on: #22533, #22528 (SafeDB).

🤖 *Co-created with Claude (Fable 5)*

Start with op-acceptance-tests/tests/supernode/** and SupernodeTestControl.InteropActivity(), then trace the stack/dsl types and the lokahi admin/test RPC surface required by the DSL. Run the existing safeheaddb_* suites and the kona-node acceptance gate. Done means the acceptance matrix runs against op-supernode and lokahi, VerifySafeHeadDatabaseMatches and SafeDB environment plumbing work cross-node, and the kona skip is removed.

Written by the indexing model from the issue text.