fix(report): classify writer failures and size CJK section budgets

Staging personal_full died as report_schema_invalid after the first
chapter blocked. Keep assertWriterOutput, stop treating refs mismatch as
missing evidence, and surface section error codes on the report APIs.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/components/personal-report/personal-report-center.tsx

@@ -19,6 +19,7 @@ type ReportListItem = Readonly<{
   themes: readonly string[];
   status: "generating" | "ready" | "failed";
   failureCode: string | null;
+  failureSummary?: string | null;
   createdAt: string;
   completedAt: string | null;
 }>;
@@ -57,6 +58,7 @@ function readReports(value: unknown): ReportListItem[] {
         : [],
       status: row.status as ReportListItem["status"],
       failureCode: typeof row.failureCode === "string" ? row.failureCode : null,
+      failureSummary: typeof row.failureSummary === "string" ? row.failureSummary : null,
       createdAt: typeof row.createdAt === "string" ? row.createdAt : "",
       completedAt: typeof row.completedAt === "string" ? row.completedAt : null,
     }];
@@ -207,7 +209,7 @@ export function PersonalReportCenter() {
                       查看进度
                     </Button>
                   ) : (
-                    <span className="report-center-failure">{report.failureCode ?? "生成失败"}</span>
+                    <span className="report-center-failure">{report.failureSummary ?? report.failureCode ?? "生成失败"}</span>
                   )}
                 </article>
               );

frontend/src/components/personal-report/personal-report-page.tsx

@@ -35,7 +35,7 @@ export type ReportLoadState =
   | { phase: "not-found" }
   | { phase: "generating"; progressPercent?: number; progressPhase?: string }
   | { phase: "timed-out" }
-  | { phase: "failed"; failureCode: string | null }
+  | { phase: "failed"; failureCode: string | null; failureSummary?: string | null }
   | { phase: "invalid"; message: string }
   | { phase: "network-error" }
   | { phase: "ready"; document: ReportDocument };
@@ -48,6 +48,7 @@ export interface ReportEnvelopeView {
   presentationMode: string;
   status: string;
   failureCode: string | null;
+  failureSummary?: string | null;
   createdAt: string;
   completedAt: string | null;
   progressPercent?: number;
@@ -104,7 +105,14 @@ export function classifyReportEnvelope(statusCode: number, json: unknown): Repor
       const code = typeof view.failureCode === "string" && view.failureCode.length > 0
         ? view.failureCode
         : null;
-      return { phase: "failed", failureCode: code };
+      const summary = typeof view.failureSummary === "string" && view.failureSummary.length > 0
+        ? view.failureSummary
+        : null;
+      return {
+        phase: "failed",
+        failureCode: code,
+        ...(summary ? { failureSummary: summary } : {}),
+      };
     }
     default:
       return { phase: "invalid", message: "报告状态无法识别。" };
@@ -293,12 +301,12 @@ export function PersonalReportPage({ reportId }: { reportId: string }) {
       <main className="flex min-h-svh flex-col items-center justify-center gap-4 px-4 text-center">
         <TriangleAlert aria-hidden="true" className="size-8 text-warning" />
         <h1 className="text-xl font-semibold text-ink">报告生成失败</h1>
+        <p className="max-w-md text-sm text-ink-secondary">
+          {state.failureSummary ?? "生成过程中出现问题，未产出可用报告。请稍后重试。"}
+        </p>
         {state.failureCode && (
           <p className="font-mono text-xs text-ink-tertiary">错误码：{state.failureCode}</p>
         )}
-        <p className="max-w-md text-sm text-ink-secondary">
-          生成过程中出现问题，未产出可用报告。请稍后重试。
-        </p>
         <Button render={<Link href="/reports" />} nativeButton={false} variant="outline">
           返回报告中心重新生成
         </Button>