fix(#196): fix race condition in job status updates

Implemented optimistic locking with version field and SELECT FOR UPDATE
transactions to prevent data corruption from concurrent job status updates.

Changes:
- Added version field to RunnerJob schema for optimistic locking
- Created migration 20260202_add_runner_job_version_for_concurrency
- Implemented ConcurrentUpdateException for conflict detection
- Updated RunnerJobsService methods with optimistic locking:
  * updateStatus() - with version checking and retry logic
  * updateProgress() - with version checking and retry logic
  * cancel() - with version checking and retry logic
- Updated CoordinatorIntegrationService with SELECT FOR UPDATE:
  * updateJobStatus() - transaction with row locking
  * completeJob() - transaction with row locking
  * failJob() - transaction with row locking
  * updateJobProgress() - optimistic locking
- Added retry mechanism (3 attempts) with exponential backoff
- Added comprehensive concurrency tests (10 tests, all passing)
- Updated existing test mocks to support updateMany

Test Results:
- All 10 concurrency tests passing ✓
- Tests cover concurrent status updates, progress updates, completions,
  cancellations, retry logic, and exponential backoff

This fix prevents race conditions that could cause:
- Lost job results (double completion)
- Lost progress updates
- Invalid status transitions
- Data corruption under concurrent access

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

apps/api/src/tasks/tasks.service.ts

@@ -1,10 +1,19 @@
 import { Injectable, NotFoundException } from "@nestjs/common";
-import { Prisma } from "@prisma/client";
+import { Prisma, Task } from "@prisma/client";
 import { PrismaService } from "../prisma/prisma.service";
 import { ActivityService } from "../activity/activity.service";
 import { TaskStatus, TaskPriority } from "@prisma/client";
 import type { CreateTaskDto, UpdateTaskDto, QueryTasksDto } from "./dto";
 
+type TaskWithRelations = Task & {
+  assignee: { id: string; name: string; email: string } | null;
+  creator: { id: string; name: string; email: string };
+  project: { id: string; name: string; color: string | null } | null;
+  subtasks?: (Task & {
+    assignee: { id: string; name: string; email: string } | null;
+  })[];
+};
+
 /**
  * Service for managing tasks
  */
@@ -18,7 +27,11 @@ export class TasksService {
   /**
    * Create a new task
    */
-  async create(workspaceId: string, userId: string, createTaskDto: CreateTaskDto) {
+  async create(
+    workspaceId: string,
+    userId: string,
+    createTaskDto: CreateTaskDto
+  ): Promise<Omit<TaskWithRelations, "subtasks">> {
     const assigneeConnection = createTaskDto.assigneeId
       ? { connect: { id: createTaskDto.assigneeId } }
       : undefined;
@@ -79,7 +92,15 @@ export class TasksService {
   /**
    * Get paginated tasks with filters
    */
-  async findAll(query: QueryTasksDto) {
+  async findAll(query: QueryTasksDto): Promise<{
+    data: Omit<TaskWithRelations, "subtasks">[];
+    meta: {
+      total: number;
+      page: number;
+      limit: number;
+      totalPages: number;
+    };
+  }> {
     const page = query.page ?? 1;
     const limit = query.limit ?? 50;
     const skip = (page - 1) * limit;
@@ -159,7 +180,7 @@ export class TasksService {
   /**
    * Get a single task by ID
    */
-  async findOne(id: string, workspaceId: string) {
+  async findOne(id: string, workspaceId: string): Promise<TaskWithRelations> {
     const task = await this.prisma.task.findUnique({
       where: {
         id,
@@ -195,7 +216,12 @@ export class TasksService {
   /**
    * Update a task
    */
-  async update(id: string, workspaceId: string, userId: string, updateTaskDto: UpdateTaskDto) {
+  async update(
+    id: string,
+    workspaceId: string,
+    userId: string,
+    updateTaskDto: UpdateTaskDto
+  ): Promise<Omit<TaskWithRelations, "subtasks">> {
     // Verify task exists
     const existingTask = await this.prisma.task.findUnique({
       where: { id, workspaceId },
@@ -305,7 +331,7 @@ export class TasksService {
   /**
    * Delete a task
    */
-  async remove(id: string, workspaceId: string, userId: string) {
+  async remove(id: string, workspaceId: string, userId: string): Promise<void> {
     // Verify task exists
     const task = await this.prisma.task.findUnique({
       where: { id, workspaceId },