Fix dataset-ref walk false positive and wire spec-mandated success toasts

- Prune the data payload and top-level datasets keys in all three ref walks
  (extractDatasetRefs, renameDatasetInSpec, resolveDatasetRefs) so a data row
  carrying a field named "data" is no longer misread as a library reference,
  spuriously rewritten, or made to throw DatasetNotFoundError. Adds tests,
  including a guard that lookup-transform refs (from.data) still resolve.
- Wire the deferred success toasts now the Toaster has landed: publish, revert,
  extract-to-dataset, and snippet/dataset delete. Copy follows the council
  title-vs-message rule (title states the action, message adds the consequence).
- Reconcile the spec's blanket toast mandate to "toast only what the user can't
  already see": no toast on visible-result creates (snippet, dataset form);
  Copy Reference stays inline and gains an aria-live announcement (new shared
  .visually-hidden utility) instead of a toast-per-copy.
- Move the toast region to bottom-right so it stops covering the header action
  cluster (Publish/Revert, theme/datasets).
- Update docs/spec 01F/02/05 and docs/architecture/07 + 10 to match.

src/app/components/SpecEditor.tsx

@@ -27,6 +27,7 @@ import { openModal } from '../modals/ModalCoordinator';
 import { useAppStore } from '../stores/AppStore';
 import { confirm } from '../stores/ConfirmStore';
 import { hasInlineData } from '../stores/ExtractStore';
+import { notify } from '../stores/NotificationStore';
 import { usePreviewStore } from '../stores/PreviewStore';
 import { selectActiveSnippet, selectShownText, useSnippetStore } from '../stores/SnippetStore';
 import { SegmentedControl, type SegmentedOption } from './SegmentedControl';
@@ -64,7 +65,14 @@ function EditorToolbar() {
   const handlePublish = () => {
     if (!useSnippetStore.getState().activeSnippetId) return;
     useSnippetStore.getState().publish();
-    // TODO: success toast "Snippet published" once the toast system lands (M6, spec §03D).
+    // Success confirmation (spec §03D). Per the council's toast-copy rule
+    // (docs/architecture/10 → Toast copy), the title states the action and the
+    // message adds the consequence rather than paraphrasing it.
+    notify({
+      kind: 'success',
+      title: 'Snippet published',
+      message: 'Your draft is now the published version.',
+    });
   };
 
   const handleRevert = async () => {
@@ -77,7 +85,11 @@ function EditorToolbar() {
     });
     if (ok) {
       useSnippetStore.getState().revert();
-      // TODO: success toast "Draft reverted" once the toast system lands (M6, spec §03D).
+      notify({
+        kind: 'success',
+        title: 'Draft reverted',
+        message: 'The editor was restored to the last published version.',
+      });
     }
   };