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/core/spec-refs.test.ts

@@ -47,6 +47,28 @@ describe('extractDatasetRefs', () => {
     // "foo" is self-defined and not a library dependency; "Library" is.
     expect(extractDatasetRefs(spec)).toEqual(['Library']);
   });
+
+  test('a data row carrying a field literally named "data" is not a reference', () => {
+    // The inline rows happen to have a column called `data` whose value looks
+    // like a reference object — it is payload, not a library dependency.
+    const spec = {
+      data: { values: [{ data: { name: 'NotARef' } }, { data: { name: 'AlsoNot' } }] },
+      mark: 'bar',
+    };
+    expect(extractDatasetRefs(spec)).toEqual([]);
+  });
+
+  test('does not descend into a self-defined datasets payload', () => {
+    const spec = { datasets: { local: [{ data: { name: 'Buried' } }] }, mark: 'bar' };
+    expect(extractDatasetRefs(spec)).toEqual([]);
+  });
+
+  test('collects a reference from a lookup transform (from.data)', () => {
+    const spec = {
+      transform: [{ lookup: 'id', from: { data: { name: 'Lookup' }, key: 'id', fields: ['x'] } }],
+    };
+    expect(extractDatasetRefs(spec)).toEqual(['Lookup']);
+  });
 });
 
 describe('recomputeDatasetRefs', () => {
@@ -105,4 +127,22 @@ describe('renameDatasetInSpec', () => {
     expect(out.data.name).toBe('Old'); // self-defined — left untouched
     expect(Object.keys(out.datasets)).toEqual(['Old']);
   });
+
+  test('does not rewrite a "data" field buried in inline data rows', () => {
+    const spec = {
+      data: { name: 'Old', values: [{ data: { name: 'Old' } }] },
+      mark: 'bar',
+    };
+    const out = renameDatasetInSpec(spec, 'Old', 'New');
+    expect(out.data.name).toBe('New'); // the real reference is renamed
+    expect(out.data.values[0].data.name).toBe('Old'); // the row payload is left alone
+  });
+
+  test('renames a reference inside a lookup transform (from.data)', () => {
+    const spec = {
+      transform: [{ lookup: 'id', from: { data: { name: 'Old' }, key: 'id' } }],
+    };
+    const out = renameDatasetInSpec(spec, 'Old', 'New');
+    expect(out.transform[0].from.data.name).toBe('New');
+  });
 });