feat(P11-P12): 落地治理开关与移动端MVP（G0-G6/H1/M1-M4）

- 新增 Feature Flag 模型、评估服务与管理 API（erp_sync/invoice_verification）\n- 完成 ERP 与验真灰度收口（路由/服务/作业统一判定）\n- 补齐 pay 与手动 sync 的 department_id 灰度上下文\n- 增加管理后台开关页、PWA 基础设施与移动拍照/审批页面\n- 增加回归脚本、安全基线与压测脚本，更新文档与执行合同\n\nIssue: G0,G1,G2,G3,G4,G5,G6,H1,M1,M2,M3,M4

server/prisma/migrations/20260211100000_feature_flags_governance/migration.sql

@@ -0,0 +1,31 @@
+CREATE TABLE "feature_flags" (
+  "id" UUID NOT NULL,
+  "flag_key" VARCHAR(64) NOT NULL,
+  "override_mode" VARCHAR(16) NOT NULL DEFAULT 'force_off',
+  "rollout_type" VARCHAR(32) NOT NULL DEFAULT 'global',
+  "department_ids" JSONB,
+  "note" TEXT,
+  "version" INTEGER NOT NULL DEFAULT 1,
+  "created_at" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+  "created_by" UUID,
+  "updated_at" TIMESTAMP(3) NOT NULL,
+  "updated_by" UUID,
+  CONSTRAINT "feature_flags_pkey" PRIMARY KEY ("id")
+);
+
+CREATE UNIQUE INDEX "feature_flags_flag_key_key" ON "feature_flags"("flag_key");
+CREATE INDEX "idx_feature_flags_key" ON "feature_flags"("flag_key");
+
+INSERT INTO "feature_flags" (
+  "id",
+  "flag_key",
+  "override_mode",
+  "rollout_type",
+  "department_ids",
+  "note",
+  "version",
+  "created_at",
+  "updated_at"
+) VALUES
+  ('6eb0ff4b-912a-4d19-8e4f-c2365604a200'::uuid, 'erp_sync', 'force_off', 'global', '[]'::jsonb, 'bootstrap default: force_off', 1, CURRENT_TIMESTAMP, CURRENT_TIMESTAMP),
+  ('6eb0ff4b-912a-4d19-8e4f-c2365604a201'::uuid, 'invoice_verification', 'force_off', 'global', '[]'::jsonb, 'bootstrap default: force_off', 1, CURRENT_TIMESTAMP, CURRENT_TIMESTAMP);