feat(ssa): Complete Phase V-A editable analysis plan variables

Features:
- Add editable variable selection in workflow plan (SingleVarSelect + MultiVarTags)
- Implement 3-layer flexible interception (warning bar + icon + blocking dialog)
- Add tool_param_constraints.json for 12 statistical tools parameter validation
- Add PATCH /workflow/:id/params API with Zod structural validation
- Implement synchronous parameter sync before execution (Promise chaining)
- Fix LLM hallucination by strict system prompt constraints
- Fix DynamicReport object-based rows compatibility (R baseline_table)
- Fix Word export row.map error with same normalization logic
- Restore inferGroupingVar for smart default variable selection
- Add ReactMarkdown rendering in SSAChatPane
- Update SSA module status document to v3.5

Modified files:
- backend: workflow.routes, ChatHandlerService, SystemPromptService, FlowTemplateService
- frontend: WorkflowTimeline, SSAWorkspacePane, DynamicReport, SSAChatPane, ssaStore, ssa.css
- config: tool_param_constraints.json (new)
- docs: SSA status doc, team review reports

Tested: Cohort study end-to-end execution + report export verified
Co-authored-by: Cursor <cursoragent@cursor.com>

frontend-v2/src/modules/ssa/components/SSAChatPane.tsx

@@ -35,6 +35,8 @@ import { useWorkflow } from '../hooks/useWorkflow';
 import { useSSAChat } from '../hooks/useSSAChat';
 import type { ChatMessage, ChatIntentType } from '../hooks/useSSAChat';
 import type { SSAMessage } from '../types';
+import ReactMarkdown from 'react-markdown';
+import remarkGfm from 'remark-gfm';
 import { TypeWriter } from './TypeWriter';
 import { DataProfileCard } from './DataProfileCard';
 import { ClarificationCard } from './ClarificationCard';
@@ -65,13 +67,12 @@ export const SSAChatPane: React.FC = () => {
   } = useSSAStore();
 
   const { uploadData, generatePlan, isUploading, uploadProgress } = useAnalysis();
-  const { generateDataProfile, handleClarify, executeWorkflow, isProfileLoading, isPlanLoading } = useWorkflow();
+  const { generateDataProfile, handleClarify, isProfileLoading, isPlanLoading } = useWorkflow();
   const {
     chatMessages,
     isGenerating,
     currentIntent,
     pendingQuestion,
-    pendingPlanConfirm,
     sendChatMessage,
     respondToQuestion,
     skipQuestion,
@@ -91,15 +92,6 @@ export const SSAChatPane: React.FC = () => {
   const chatEndRef = useRef<HTMLDivElement>(null);
   const messagesContainerRef = useRef<HTMLDivElement>(null);
 
-  // Phase IV: plan_confirmed → 自动触发 executeWorkflow
-  useEffect(() => {
-    if (pendingPlanConfirm?.workflowId && currentSession?.id) {
-      executeWorkflow(currentSession.id, pendingPlanConfirm.workflowId).catch((err: any) => {
-        addToast(err?.message || '执行失败', 'error');
-      });
-    }
-  }, [pendingPlanConfirm, currentSession?.id, executeWorkflow, addToast]);
-
   // Phase II: session 切换时加载对话历史
   useEffect(() => {
     if (currentSession?.id) {
@@ -417,7 +409,11 @@ export const SSAChatPane: React.FC = () => {
                     <span>{msg.content}</span>
                   </div>
                 ) : (
-                  <div className="chat-msg-content">{msg.content}</div>
+                  <div className="chat-msg-content">
+                    <ReactMarkdown remarkPlugins={[remarkGfm]}>
+                      {msg.content}
+                    </ReactMarkdown>
+                  </div>
                 )}
               </div>
             </div>