fix(web): align the context separator with ToolRow and name the caption

Review follow-ups on the context provenance row:

- the producer name now follows ToolRow's aria-hidden separator dot instead
  of a literal middot inside the text, so the two disclosure rows expose one
  accessible-name shape;
- the English steering caption becomes the noun `Interjection`, parallel to
  the Chinese 插话 and to the label this bubble carried before;
- the history fold gets its own provenance assertion, so the mapping it
  declares separately from TranscriptAdapter is pinned on both sides;
- the superseded-in-part bullet on the no-interjection-chrome note now
  enumerates the third Decision bullet too, whose no-badge and no-IconActions
  clauses had both lapsed.

packages/client/ui-conversation/src/client/chat/ContextInjectionRow.module.css

@@ -12,13 +12,21 @@
   color: var(--dsw-alias-label-secondary);
 }
 
-/* Producer name beside the role title: ToolRow's summary geometry, so the two
-   disclosure rows keep one 24px rhythm; subordinate color, truncated when long. */
+/* Separator and producer name beside the role title: ToolRow's summary geometry,
+   so the two disclosure rows keep one 24px rhythm and one separator shape. */
+.sep {
+  flex: none;
+  width: 2px;
+  height: 2px;
+  margin: 0 8px;
+  border-radius: 1px;
+  background: var(--dsw-alias-label-caption);
+}
+
 .source {
   flex: 1 1 auto;
   min-width: 0;
   overflow: hidden;
-  margin-left: 4px;
   color: var(--dsw-alias-label-tertiary);
   font-size: 14px;
   line-height: 24px;

packages/client/ui-conversation/src/client/chat/ContextInjectionRow.tsx

@@ -80,7 +80,13 @@ export function ContextInjectionRow({ content, source, provenance, t }: ContextI
       chevronClassName={css.chevron}
       title={t(provenance.role === 'recall' ? 'message.contextRecall' : 'message.contextInjection')}
       collapsedContent={provenance.label === null ? undefined : (
-        <span className={css.source} data-context-source>{`· ${provenance.label}`}</span>
+        /* ToolRow's separator shape: an aria-hidden dot, so the accessible name
+           stays the two readable parts and the two disclosure rows expose one
+           name shape. A source that names no producer drops the dot with it. */
+        <>
+          <span className={css.sep} aria-hidden />
+          <span className={css.source} data-context-source>{provenance.label}</span>
+        </>
       )}
       keepContentWhenOpen
       open={open}

packages/client/ui-conversation/src/client/locales.ts

@@ -166,7 +166,7 @@ export const en = {
   'message.extraBlock': 'Extra content block',
   'message.contextInjection': 'Context injection',
   'message.contextRecall': 'Session recall',
-  'message.steering': 'Steer',
+  'message.steering': 'Interjection',
   'message.compaction': 'Context compacted',
   'message.compaction.expand': 'View compaction summary',
   'message.compaction.unavailable': 'Compaction summary unavailable',