feat(server): 完成 P3 后端API与回归（D2~D9）

- workflow: 任务详情/转审候选/列表分页字段（D5）
- reimbursements: 列表API + pay凭证字段/幂等增强（D7）
- invoice-pool: 列表/详情API + 上传pending_ocr（D9）
- ocr/audit: mock provider + 回归脚本 + regression-all开关（D2/D3）
- CI: 新增 ci-minimal / ci-regression 工作流（D4）

server/src/services/ocr/index.js

@@ -1,10 +1,19 @@
 const { runTencentVatOcr } = require("./tencent");
+const { runMockOcr } = require("./mock");
 
 function isOcrEnabledForType(config, ocrType) {
+  if (config.ocrProvider === "mock") {
+    return true;
+  }
+
   return config.ocrProvider === "tencent" && ocrType === "vat";
 }
 
 async function runOcrForInvoice({ config, ocrType, imageBase64 }) {
+  if (config.ocrProvider === "mock") {
+    return runMockOcr({ ocrType, imageBase64 });
+  }
+
   if (config.ocrProvider !== "tencent") {
     throw new Error(`Unsupported OCR provider: ${config.ocrProvider}`);
   }

server/src/services/ocr/mock.js

@@ -0,0 +1,60 @@
+const crypto = require("node:crypto");
+
+function decodeMarker(imageBase64) {
+  try {
+    return Buffer.from(imageBase64, "base64").toString("utf8");
+  } catch {
+    return "";
+  }
+}
+
+function buildInvoiceKey(markerText) {
+  const duplicateMatch = markerText.match(/MOCK_DUP:([A-Za-z0-9_-]+)/);
+  if (duplicateMatch?.[1]) {
+    return `dup:${duplicateMatch[1]}`;
+  }
+
+  const hash = crypto.createHash("sha256").update(markerText || "mock-empty").digest("hex");
+  return `hash:${hash.slice(0, 20)}`;
+}
+
+function toAmount(seedHex, fallback) {
+  const value = Number.parseInt(seedHex.slice(0, 8), 16);
+  if (!Number.isFinite(value)) {
+    return fallback;
+  }
+
+  return ((value % 50000) / 100 + fallback).toFixed(2);
+}
+
+async function runMockOcr({ ocrType, imageBase64 }) {
+  const markerText = decodeMarker(imageBase64);
+  if (markerText.includes("MOCK_OCR_FAIL")) {
+    throw new Error("mock_ocr_failed");
+  }
+
+  const invoiceKey = buildInvoiceKey(markerText);
+  const hash = crypto.createHash("sha256").update(invoiceKey).digest("hex");
+  const invoiceCode = `MOCK${hash.slice(0, 8).toUpperCase()}`;
+  const invoiceNumber = hash.slice(8, 16).toUpperCase();
+
+  return {
+    invoiceCode,
+    invoiceNumber,
+    invoiceDate: "2026-02-08",
+    amount: toAmount(hash.slice(16, 24), 100),
+    taxAmount: toAmount(hash.slice(24, 32), 10),
+    totalAmount: toAmount(hash.slice(32, 40), 110),
+    sellerName: `Mock Seller (${ocrType})`,
+    buyerName: "Mock Buyer",
+    raw: {
+      provider: "mock",
+      invoiceKey,
+      marker: markerText.slice(0, 128),
+    },
+  };
+}
+
+module.exports = {
+  runMockOcr,
+};