merge: 集成V2.6 性能增强与小宝后台化

# Conflicts:
#	apps/server/prisma/schema.prisma
#	apps/server/src/app.module.ts
#	apps/web/components/layout/Sidebar.tsx
#	docs/architecture.md
#	docs/decisions.md
#	docs/roadmap.md

apps/server/prisma/migrations/20260708030000_v26_hot_query_indexes/migration.sql

@@ -0,0 +1,44 @@
+-- V2.6 hot query indexes for performance harness, query budget audit,
+-- and background Xiaobao summary refresh scans.
+
+CREATE INDEX IF NOT EXISTS "projects_product_created_at_idx"
+  ON "projects"("product_id", "created_at" DESC);
+
+CREATE INDEX IF NOT EXISTS "versions_product_created_at_idx"
+  ON "versions"("product_id", "created_at" DESC);
+
+CREATE INDEX IF NOT EXISTS "versions_product_project_created_at_idx"
+  ON "versions"("product_id", "project_id", "created_at" DESC);
+
+CREATE INDEX IF NOT EXISTS "version_plans_owner_open_due_idx"
+  ON "version_plans"("owner_id", "expected_end_at" ASC, "updated_at" DESC)
+  WHERE "status" <> 'completed';
+
+CREATE INDEX IF NOT EXISTS "dev_tasks_assignee_open_priority_idx"
+  ON "dev_tasks"("assignee_id", "priority" ASC, "updated_at" DESC)
+  WHERE "status" <> 'submitted';
+
+CREATE INDEX IF NOT EXISTS "test_cases_assignee_open_priority_idx"
+  ON "test_cases"("assignee_id", "priority" ASC, "updated_at" DESC)
+  WHERE "status" NOT IN ('passed', 'failed', 'blocked');
+
+CREATE INDEX IF NOT EXISTS "bugs_version_status_priority_updated_at_idx"
+  ON "bugs"("version_id", "status" ASC, "priority" ASC, "updated_at" DESC);
+
+CREATE INDEX IF NOT EXISTS "bugs_assignee_open_priority_idx"
+  ON "bugs"("assignee_id", "priority" ASC, "updated_at" DESC)
+  WHERE "status" IN ('open', 'fixing', 'fixed', 'verifying');
+
+CREATE INDEX IF NOT EXISTS "test_cases_version_round_status_updated_at_desc_idx"
+  ON "test_cases"("version_id", "round_no" DESC, "status" ASC, "updated_at" DESC);
+
+CREATE INDEX IF NOT EXISTS "xiaobao_risk_summaries_warning_score_idx"
+  ON "xiaobao_risk_summaries"("risk_score" DESC, "updated_at" DESC)
+  WHERE "risk_level" <> 'on_track';
+
+CREATE INDEX IF NOT EXISTS "xiaobao_risk_summaries_dirty_updated_at_idx"
+  ON "xiaobao_risk_summaries"("updated_at" ASC)
+  WHERE "dirty" = true;
+
+CREATE INDEX IF NOT EXISTS "work_activities_version_occurred_at_idx"
+  ON "work_activities"("version_id", "occurred_at" DESC);

apps/server/prisma/migrations/20260708040000_v26_background_jobs/migration.sql

@@ -0,0 +1,32 @@
+CREATE TABLE "background_jobs" (
+    "id" TEXT NOT NULL,
+    "type" TEXT NOT NULL,
+    "status" TEXT NOT NULL DEFAULT 'queued',
+    "dedupe_key" TEXT,
+    "payload" JSONB NOT NULL DEFAULT '{}',
+    "attempts" INTEGER NOT NULL DEFAULT 0,
+    "max_attempts" INTEGER NOT NULL DEFAULT 3,
+    "available_at" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "locked_by" TEXT,
+    "locked_until" TIMESTAMP(3),
+    "last_error" TEXT,
+    "completed_at" TIMESTAMP(3),
+    "created_at" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "updated_at" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+
+    CONSTRAINT "background_jobs_pkey" PRIMARY KEY ("id")
+);
+
+CREATE INDEX "background_jobs_status_available_at_idx"
+  ON "background_jobs"("status", "available_at" ASC, "created_at" ASC);
+
+CREATE INDEX "background_jobs_type_status_available_at_idx"
+  ON "background_jobs"("type", "status", "available_at" ASC);
+
+CREATE INDEX "background_jobs_lease_idx"
+  ON "background_jobs"("status", "locked_until" ASC)
+  WHERE "locked_until" IS NOT NULL;
+
+CREATE UNIQUE INDEX "background_jobs_active_dedupe_key_idx"
+  ON "background_jobs"("type", "dedupe_key")
+  WHERE "dedupe_key" IS NOT NULL AND "status" IN ('queued', 'running');

apps/server/prisma/schema.prisma

@@ -443,6 +443,25 @@ model AuditEvent {
   @@map("audit_events")
 }
 
+model BackgroundJob {
+  id          String   @id @default(cuid())
+  type        String
+  status      String   @default("queued")
+  dedupeKey   String?  @map("dedupe_key")
+  payload     Json     @default("{}")
+  attempts    Int      @default(0)
+  maxAttempts Int      @default(3) @map("max_attempts")
+  availableAt DateTime @default(now()) @map("available_at")
+  lockedBy    String?  @map("locked_by")
+  lockedUntil DateTime? @map("locked_until")
+  lastError   String?  @map("last_error")
+  completedAt DateTime? @map("completed_at")
+  createdAt   DateTime @default(now()) @map("created_at")
+  updatedAt   DateTime @updatedAt @map("updated_at")
+
+  @@map("background_jobs")
+}
+
 model XiaobaoRiskSummary {
   versionId           String   @id @map("version_id")
   riskLevel           String   @map("risk_level")