fix(vendor): widen include's writeTask for exactOptionalPropertyTypes

The debounced writer assigns undefined on flush, which a plain optional
NodeJS.Timeout rejects under exactOptionalPropertyTypes; the error had
been masked by stale build state until a residue cleanup invalidated it.
Logged as local modification 14 in the vendor manifest.

vendor/include/src/index.ts

@@ -170,7 +170,7 @@ export class Include extends EntryTree {
   private readonly: boolean
   private content?: string
   private data?: EntryOptions[]
-  private writeTask?: NodeJS.Timeout
+  private writeTask?: NodeJS.Timeout | undefined
   private applyQueue: Promise<unknown> = Promise.resolve()
 
   constructor(ctx: Context, public config: Include.Config) {