feat(ssa): Agent channel UX optimization (Solution B) + Plan-and-Execute architecture design

SSA Agent channel improvements (12 code files, +931/-203 lines):
- Solution B: left/right separation of concerns (gaze guiding + state mutex + time-travel)
- JWT token refresh mechanism (ensureFreshToken) to fix HTTP 401 during pipeline
- Code truncation fix: LLM maxTokens 4000->8000 + CSS max-height 60vh
- Retry streaming code generation with generateCodeStream()
- R Docker structured errors: 20+ pattern matching + format_agent_error + line extraction
- Prompt iron rules: strict output format in CoderAgent System Prompt
- parseCode robustness: XML/Markdown/inference 3-tier matching + length validation
- consoleOutput type defense: handle both array and scalar from R Docker unboxedJSON
- Agent progress bar sync: derive phase from agentExecution.status
- Export report / view code buttons restored for Agent mode
- ExecutingProgress component: real-time timer + dynamic tips + step pulse animation

Architecture design (3 review reports):
- Plan-and-Execute step-by-step execution architecture approved
- Code accumulation strategy (R Docker stays stateless)
- 5 engineering guardrails: XML tags, AST pre-check, defensive prompts, high-fidelity schema, error classification circuit breaker

Docs: update SSA module status v4.1, system status v6.7, deployment changelist
Made-with: Cursor

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

@@ -14,6 +14,8 @@ export const SSACodeModal: React.FC = () => {
     addToast,
     currentRecordId,
     analysisHistory,
+    executionMode,
+    agentExecution,
   } = useSSAStore();
 
   const [code, setCode] = useState<string>('');
@@ -27,26 +29,31 @@ export const SSACodeModal: React.FC = () => {
     if (!codeModalVisible) return;
     setIsLoading(true);
     try {
-      const steps = record?.steps ?? [];
-      const successSteps = steps.filter(
-        (s) => (s.status === 'success' || s.status === 'warning') && s.result
-      );
-      if (successSteps.length > 0) {
-        const allCode = successSteps
-          .map((s) => {
-            const stepCode = (s.result as any)?.reproducible_code;
-            const header = `# ========================================\n# 步骤 ${s.step_number}: ${s.tool_name}\n# ========================================\n`;
-            return header + (stepCode || '# 该步骤暂无可用代码');
-          })
-          .join('\n\n');
-        setCode(allCode);
+      if (executionMode === 'agent' && agentExecution?.generatedCode) {
+        const header = `# ========================================\n# Agent 生成的 R 代码\n# 分析任务: ${agentExecution.query || '统计分析'}\n# ========================================\n`;
+        setCode(header + agentExecution.generatedCode);
       } else {
-        setCode('# 暂无可用代码\n# 请先执行分析');
+        const steps = record?.steps ?? [];
+        const successSteps = steps.filter(
+          (s) => (s.status === 'success' || s.status === 'warning') && s.result
+        );
+        if (successSteps.length > 0) {
+          const allCode = successSteps
+            .map((s) => {
+              const stepCode = (s.result as any)?.reproducible_code;
+              const header = `# ========================================\n# 步骤 ${s.step_number}: ${s.tool_name}\n# ========================================\n`;
+              return header + (stepCode || '# 该步骤暂无可用代码');
+            })
+            .join('\n\n');
+          setCode(allCode);
+        } else {
+          setCode('# 暂无可用代码\n# 请先执行分析');
+        }
       }
     } finally {
       setIsLoading(false);
     }
-  }, [codeModalVisible, record]);
+  }, [codeModalVisible, record, executionMode, agentExecution]);
 
   if (!codeModalVisible) return null;
 
@@ -56,7 +63,10 @@ export const SSACodeModal: React.FC = () => {
     const now = new Date();
     const pad = (n: number) => n.toString().padStart(2, '0');
     const ts = `${now.getFullYear()}${pad(now.getMonth() + 1)}${pad(now.getDate())}_${pad(now.getHours())}${pad(now.getMinutes())}${pad(now.getSeconds())}`;
-    const title = (record?.plan?.title || 'analysis')
+    const rawTitle = executionMode === 'agent'
+      ? (agentExecution?.query || 'agent_analysis')
+      : (record?.plan?.title || 'analysis');
+    const title = rawTitle
       .replace(/[^a-zA-Z0-9\u4e00-\u9fa5_-]/g, '_')
       .slice(0, 30);
     return `SSA_${title}_${ts}.R`;