feat: remove legacy OpenCode runtime

Cut product flows over to Coding/Pi and retain only the migration-owned v1 boundary. Promote supported native optional packages because electron-builder omitted pnpm transitive optional closure from the packaged ASAR.

src/pages/Chat/CodingChatPanel.tsx

@@ -106,6 +106,7 @@ export function CodingChatPanel({
   const createConversation = useCodingWorkspaceStore((state) => state.createConversation);
   const patchConversation = useCodingWorkspaceStore((state) => state.patchConversation);
   const upsertConversation = useCodingWorkspaceStore((state) => state.upsertConversation);
+  const acknowledgeLegacyNotice = useCodingWorkspaceStore((state) => state.acknowledgeLegacyNotice);
 
   const selectedConversationId = useCodingConversationStore((state) => state.selectedConversationId);
   const connectionState = useCodingConversationStore((state) => state.connectionState);
@@ -663,6 +664,23 @@ export function CodingChatPanel({
           onOpenSettings={onOpenProjectSettings}
         />
 
+        {config?.legacyConversationNotice === 'pending' && (
+          <div className="mx-4 mt-3 flex min-h-10 items-center gap-3 rounded-xl border border-amber-300/70 bg-amber-50 px-3 py-2 text-xs text-amber-950 sm:mx-5" data-testid="legacy-conversation-notice">
+            <CircleAlert className="h-4 w-4 shrink-0" aria-hidden="true" />
+            <p className="min-w-0 flex-1 text-pretty">
+              旧版 OpenCode 对话不能在 Pi 中继续；原数据已保留，仅用于旧版本回滚或导出。
+            </p>
+            <Button
+              type="button"
+              variant="ghost"
+              className="min-h-10 shrink-0 rounded-xl px-3 text-amber-950"
+              onClick={() => void acknowledgeLegacyNotice()}
+            >
+              知道了
+            </Button>
+          </div>
+        )}
+
         {(workspaceError || conversationMetadataError || connectionError) && (
           <div className="mx-4 mt-3 flex min-h-10 items-center gap-2 rounded-xl bg-destructive/5 px-3 py-2 text-xs text-destructive sm:mx-5">
             <CircleAlert className="h-4 w-4 shrink-0" aria-hidden="true" />