feat(acp): surface Claude API retry state in chat input

Enable raw Claude SDK forwarding for ACP sessions and emit only system/api_retry events to the frontend.

Show a localized single-line retry banner with loading under the conversation input, including error details and retry progress.

src/components/conversations/conversation-detail-panel.tsx

@@ -877,6 +877,7 @@ const ConversationTabView = memo(function ConversationTabView({
       defaultPath={workingDirForConnection}
       agentName={AGENT_LABELS[selectedAgent]}
       error={conn.error}
+      claudeApiRetry={conn.claudeApiRetry}
       pendingPermission={conn.pendingPermission}
       pendingQuestion={conn.pendingQuestion}
       onFocus={handleFocus}