Static promises cross into the island as real engine thenables; Promise.all over mixed island/static entries runs the engine's own combinator

- jsvalIn (and the island-literal member path behind it) accepts STATIC promises whose fulfillment is in the reverse bridge's payload domain — void/number/boolean/string/'any', plus the NEW Promise<any[]> payload (SCR_ISLP_JSVAL_ARR: a native array of engine cells re-enters as a fresh engine array over the SAME engine values). scr_jsval_from_promise emits from jsMarshal in both backends; the IR validator admits the arm.
- Promise.all with MIXED entries where some entry is an island value (the withPlugins shape: Promise.all([loadBuiltinPlugins(), loadPlugins(plugins)])) lowers to the ENGINE's own Promise.all — island entries pass through, static promises bridge as thenables, and the combined result stays an island value the static side awaits through the existing island→static bridge. All-static tuples keep the typed fence hint.
- Corpus 2605 (unawaited static promise in an 'any' slot answers typeof "object" and awaits engine-side; the mixed-all + .flat() chain) is byte-identical to Node under both backends; SAN clean. Composite fulfillments (Promise<{...}[]>) stay fenced with the promise type named — the payload-domain residue.