feat(consult): add free model-classified smalltalk fast path

Keep full consultation tool contracts unchanged. Persist short replies and refund the original reservation atomically while recording actual model usage. Verify Linux frontend 3566/3566, database 40/40, Static home and gzip +0.0493%.

Co-Authored-By: Claude Code <noreply@anthropic.com>

frontend/src/components/chat-transcript.tsx

@@ -42,6 +42,7 @@ export type ChatTranscriptProps = Readonly<{
   streamingThinking?: string;
   streamingSections?: readonly PublicThinkingSection[];
   streamingTimeline?: readonly ConsultationTimelineRow[];
+  streamingResponseKind?: "smalltalk";
   sessionId: string;
   sessionType: "consultation" | "birth_time_rectification";
   theme?: ConsultationDomain;
@@ -197,6 +198,7 @@ export const ChatTranscript = memo(function ChatTranscript({
   streamingThinking,
   streamingSections,
   streamingTimeline,
+  streamingResponseKind,
   sessionId,
   sessionType,
   theme,
@@ -214,6 +216,7 @@ export const ChatTranscript = memo(function ChatTranscript({
     streamingThinking,
     streamingSections,
     streamingTimeline,
+    streamingResponseKind,
   );
 
   return (
@@ -260,6 +263,7 @@ export function UnsplitChatTranscript({
   streamingThinking,
   streamingSections,
   streamingTimeline,
+  streamingResponseKind,
   sessionId,
   sessionType,
   theme,
@@ -278,6 +282,7 @@ export function UnsplitChatTranscript({
     streamingThinking,
     streamingSections,
     streamingTimeline,
+    streamingResponseKind,
   );
   return (
     <>