fix(ssa): Fix 7 integration bugs and refactor frontend unified state management

Bug fixes:
- Fix garbled error messages in chat (TypeWriter rendering issue)
- Fix R engine NA crash in descriptive.R (defensive isTRUE/is.na checks)
- Fix intent misclassification for statistical significance queries
- Fix step 2 results not displayed (accept warning status alongside success)
- Fix incomplete R code download (only step 1 included)
- Fix multi-task state confusion (clicking old card shows new results)
- Add R engine and backend parameter logging for debugging

Refactor - Unified Record Architecture:
- Replace 12 global singleton fields with AnalysisRecord as single source of truth
- Remove isWorkflowMode branching across all components
- One Analysis = One Record = N Steps paradigm
- selectRecord only sets currentRecordId, all rendering derives from currentRecord
- Fix cross-hook-instance issue: executeWorkflow fallback to store currentRecordId

Updated files: ssaStore, useWorkflow, useAnalysis, SSAChatPane, SSAWorkspacePane,
SSACodeModal, WorkflowTimeline, QueryService, WorkflowExecutorService, descriptive.R

Tested: Manual integration test passed - multi-task switching, R code completeness
Co-authored-by: Cursor <cursoragent@cursor.com>

r-statistics-service/plumber.R

@@ -187,6 +187,16 @@ function(req, tool_code) {
     # 解析请求体
     input <- jsonlite::fromJSON(req$postBody, simplifyVector = FALSE)
     
+    # 记录传入参数（便于调试）
+    param_names <- if (!is.null(input$params)) paste(names(input$params), collapse=", ") else "NULL"
+    message(glue::glue("[Skill:{tool_code}] params keys: [{param_names}]"))
+    if (!is.null(input$params$variables)) {
+      message(glue::glue("[Skill:{tool_code}] variables ({length(input$params$variables)}): [{paste(input$params$variables, collapse=', ')}]"))
+    }
+    if (!is.null(input$params$group_var)) {
+      message(glue::glue("[Skill:{tool_code}] group_var: {input$params$group_var}"))
+    }
+
     # Debug 模式：保留临时文件用于排查
     debug_mode <- isTRUE(input$debug)
     
@@ -248,7 +258,7 @@ function(req, tool_code) {
     return(result)
     
   }, error = function(e) {
-    # 使用友好错误映射
+    message(glue::glue("[Skill:{tool_code}] ERROR: {e$message}"))
     return(map_r_error(e$message))
   })
 }