fix(reasoning): persist canonical history for DeepSeek and web chat

web/frontend/src/api/sessions.ts

@@ -14,6 +14,7 @@ export interface SessionDetail {
   messages: {
     role: "user" | "assistant"
     content: string
+    kind?: "normal" | "thought"
     media?: string[]
     attachments?: {
       type?: "image" | "audio" | "video" | "file"

web/frontend/src/features/chat/history.ts

@@ -45,7 +45,8 @@ export async function loadSessionMessages(
     id: `hist-${index}-${Date.now()}`,
     role: message.role,
     content: message.content,
-    kind: message.role === "assistant" ? "normal" : undefined,
+    kind:
+      message.role === "assistant" ? (message.kind ?? "normal") : undefined,
     attachments: toChatAttachments({
       media: message.media,
       attachments: message.attachments,