docs(spec): TOP_LEVEL_COLLECTIONS_NEVER_RESIDUAL names the readers the tree has

The docblock said top-level datasets are consumed by AppPlugin straight off
the bundle. AppPlugin reads no datasets; a package body's datasets are read
by the engine's registerApp METADATA_ARRAY_KEYS loop, and nothing reads a
top-level datasets item no body declares.

Claude-Session: https://claude.ai/code/session_01JQwxbad6xiDCcLYXcBsEa6
Co-authored-by: Claude <noreply@anthropic.com>

Author: claude

packages/spec/src/stack.zod.ts

@@ -361,11 +361,17 @@ function applyCollectionItemOwnerStampGate(
  * The judged collections a `packages[]` stack's TOP LEVEL never files as
  * residual items: the boot's residual rule (`unclaimedTopLevel`,
  * `@objectstack/metadata`) walks the collections the metadata door registers
- * as items (its `ARTIFACT_FIELD_TO_TYPE`), and these three are not among them.
- * The boot reads them off the stack whole and judges no stamp on them: seed
- * `data` is applied by the seed loader, `jobs` are scheduled and `datasets`
- * consumed by `AppPlugin` straight off the bundle. A package BODY's items of
- * these collections are still judged, at both doors.
+ * as items (its `ARTIFACT_FIELD_TO_TYPE`), and these three are not among them,
+ * so the boot judges no stamp on a top-level item of any of them. Their readers
+ * differ:
+ *  - seed `data` and `jobs` are read off the stack whole, the top level merged
+ *    with every body (`resolveArtifactCollections`, `@objectstack/runtime`):
+ *    `AppPlugin` hands the seed `data` to the seed loader and schedules the
+ *    `jobs`;
+ *  - `datasets` are read off the package BODIES only, by the engine's
+ *    `registerApp` (its `METADATA_ARRAY_KEYS` loop, `@objectstack/objectql`).
+ *    No boot reader takes a top-level `datasets` item that no body declares.
+ * A package BODY's items of these collections are still judged, at both doors.
  *
  * Mirrored, because `@objectstack/spec` cannot import the rule it mirrors; a
  * `@objectstack/metadata` test holds the two equal, collection by collection.