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/prisma/migrations/20260202_add_runner_job_version_for_concurrency/migration.sql

@@ -0,0 +1,7 @@
+-- Add version field for optimistic locking to prevent race conditions
+-- This allows safe concurrent updates to runner job status
+
+ALTER TABLE "runner_jobs" ADD COLUMN "version" INTEGER NOT NULL DEFAULT 1;
+
+-- Create index for better performance on version checks
+CREATE INDEX "runner_jobs_version_idx" ON "runner_jobs"("version");

apps/api/prisma/schema.prisma

@@ -1135,6 +1135,7 @@ model RunnerJob {
   status          RunnerJobStatus @default(PENDING)
   priority        Int
   progressPercent Int             @default(0) @map("progress_percent")
+  version         Int             @default(1) // Optimistic locking version
 
   // Results
   result Json?