21.2 review remediation: pause-spin, OQ7 comment, rename, C2 cross-check

Skip the back-pressure interop poll while paused (UC5). Document complete()
draining the stash in full by design. Rename scheduler isProductionPaused to
evaluateProductionPause (latch-advancing); window exposure name unchanged.

DeepDrftPublic/Interop/audio/OpusStreamDecoder.ts

@@ -191,6 +191,12 @@ export class OpusStreamDecoder implements IStreamingDecoder {
         // End-of-stream may arrive while still throttled with bytes stashed (e.g. a short track
         // that finished sending before the scheduler drained). Configure if needed and replay the
         // stash so the tail is decoded before flush — otherwise the final seconds would be lost.
+        //
+        // OQ7/AC1-Opus precision note: the stash here is drained in full without a water-mark
+        // check. This is intentionally correct: the stream has ended — you cannot back-pressure a
+        // finished stream — and the remainder is tail-only (bounded by whatever the throttled C#
+        // loop left in flight, which is at most one push() worth of bytes). Adding a water-mark
+        // gate to complete() would silently drop the track's tail and is therefore wrong.
         if (this.pendingBytes.length > 0) {
             if (await this.ensureConfigured()) {
                 const stashed = this.pendingBytes;