sea-operation: refresh test fakes for the merged-kernel binding surface

Rebased onto the updated sea-results. Makes the StatementStub
(SeaIntervalParity) and the local NativeStatement interface (lifecycle
e2e) use a synchronous schema() to match the merged-kernel binding, so the
specs type-check against SeaOperationStatement.

Co-authored-by: Isaac

Author: msrathore-db

tests/e2e/sea/operation-lifecycle-e2e.test.ts

@@ -69,7 +69,8 @@ interface NativeConnection {
 
 interface NativeStatement {
   fetchNextBatch(): Promise<{ ipcBytes: Buffer } | null>;
-  schema(): Promise<{ ipcBytes: Buffer }>;
+  // schema() is synchronous on the merged-kernel binding.
+  schema(): { ipcBytes: Buffer };
   cancel(): Promise<void>;
   close(): Promise<void>;
 }

tests/unit/sea/SeaIntervalParity.test.ts

@@ -85,7 +85,8 @@ class StatementStub {
     return { ipcBytes: this.batches.shift() as Buffer };
   }
 
-  public async schema(): Promise<{ ipcBytes: Buffer }> {
+  // schema() is synchronous on the merged-kernel binding.
+  public schema(): { ipcBytes: Buffer } {
     return { ipcBytes: this.schemaIpc };
   }