Wire the app, worker, and cleanup entry points onto Prisma Client

Task 4 rewrote src/db.js and src/jobs/jobRepository.js to use Prisma
instead of the hand-rolled mariadb pool. This updates every remaining
call site (app.js, server.js, worker.js, cleanup.js) and the 5 test
files that still referenced getPool/closePool/pool.query, so the app
and full test suite compile and run against Prisma Client.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

test/api/endToEnd.test.js

@@ -5,34 +5,34 @@ import path from 'node:path';
 import os from 'node:os';
 import { Document, Paragraph, TextRun, Packer } from 'docx';
 import { createApp } from '../../src/app.js';
-import { getPool, closePool } from '../../src/db.js';
+import { getPrismaClient, closePrismaClient } from '../../src/db.js';
 import { loadConfig } from '../../src/config.js';
 import { ensureStorageDirs } from '../../src/storage.js';
 import { processPendingJobs } from '../../src/worker.js';
 
 let app;
-let pool;
+let prisma;
 let config;
 
 beforeAll(async () => {
   config = { ...loadConfig(), storageDir: await fs.mkdtemp(path.join(os.tmpdir(), 'converter-e2e-')) };
   await ensureStorageDirs(config);
-  pool = getPool(config);
-  app = createApp(config, pool);
+  prisma = getPrismaClient(config);
+  app = createApp(config, prisma);
 });
 
 afterAll(async () => {
-  await closePool();
+  await closePrismaClient();
   await fs.rm(config.storageDir, { recursive: true, force: true });
 });
 
 beforeEach(async () => {
-  await pool.query('DELETE FROM conversion_jobs');
+  await prisma.conversionJob.deleteMany();
 });
 
 async function waitForDone(id, maxAttempts = 20) {
   for (let attempt = 0; attempt < maxAttempts; attempt += 1) {
-    await processPendingJobs(pool, config);
+    await processPendingJobs(prisma, config);
     const response = await request(app).get(`/api/jobs/${id}`);
     if (response.body.status === 'done' || response.body.status === 'failed') {
       return response.body;