feat: add conversion_jobs repository

Also configures the MariaDB pool with timezone: 'auto', since the
default 'local' mode sends dates without timezone conversion and
silently broke expires_at comparisons whenever the app host and DB
server clocks differ (caught by the findExpiredJobs test).

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

src/db.js

@@ -10,6 +10,7 @@ export function getPool(config) {
       password: config.db.password,
       database: config.db.database,
       connectionLimit: 10,
+      timezone: 'auto',
     });
   }
   return pool;

src/jobs/jobRepository.js

@@ -0,0 +1,96 @@
+function toCamelJob(row) {
+  if (!row) return null;
+  return {
+    id: row.id,
+    status: row.status,
+    family: row.family,
+    sourceFormat: row.source_format,
+    targetFormat: row.target_format,
+    originalFilename: row.original_filename,
+    inputPath: row.input_path,
+    outputPath: row.output_path,
+    inputMimeType: row.input_mime_type,
+    outputMimeType: row.output_mime_type,
+    errorMessage: row.error_message,
+    createdAt: row.created_at,
+    updatedAt: row.updated_at,
+    expiresAt: row.expires_at,
+  };
+}
+
+export async function createJob(pool, job) {
+  await pool.query(
+    `INSERT INTO conversion_jobs
+      (id, status, family, source_format, target_format, original_filename, input_path, input_mime_type, expires_at)
+     VALUES (?, 'pending', ?, ?, ?, ?, ?, ?, ?)`,
+    [
+      job.id,
+      job.family,
+      job.sourceFormat,
+      job.targetFormat,
+      job.originalFilename,
+      job.inputPath,
+      job.inputMimeType,
+      job.expiresAt,
+    ]
+  );
+}
+
+export async function getJobById(pool, id) {
+  const rows = await pool.query(
+    `SELECT id, status, family, source_format, target_format, original_filename,
+            input_path, output_path, input_mime_type, output_mime_type,
+            error_message, created_at, updated_at, expires_at
+     FROM conversion_jobs WHERE id = ?`,
+    [id]
+  );
+  return toCamelJob(rows[0]);
+}
+
+export async function getJobErrorLog(pool, id) {
+  const rows = await pool.query('SELECT error_log FROM conversion_jobs WHERE id = ?', [id]);
+  return rows[0]?.error_log ?? null;
+}
+
+export async function markProcessing(pool, id) {
+  await pool.query("UPDATE conversion_jobs SET status = 'processing' WHERE id = ?", [id]);
+}
+
+export async function markDone(pool, id, { outputPath, outputMimeType }) {
+  await pool.query(
+    "UPDATE conversion_jobs SET status = 'done', output_path = ?, output_mime_type = ? WHERE id = ?",
+    [outputPath, outputMimeType, id]
+  );
+}
+
+export async function markFailed(pool, id, { errorMessage, errorLog }) {
+  await pool.query(
+    "UPDATE conversion_jobs SET status = 'failed', error_message = ?, error_log = ? WHERE id = ?",
+    [errorMessage, errorLog, id]
+  );
+}
+
+export async function findPendingJobs(pool, limit) {
+  const rows = await pool.query(
+    `SELECT id, status, family, source_format, target_format, original_filename,
+            input_path, output_path, input_mime_type, output_mime_type,
+            error_message, created_at, updated_at, expires_at
+     FROM conversion_jobs WHERE status = 'pending' ORDER BY created_at ASC LIMIT ?`,
+    [limit]
+  );
+  return rows.map(toCamelJob);
+}
+
+export async function findExpiredJobs(pool) {
+  const rows = await pool.query(
+    `SELECT id, status, family, source_format, target_format, original_filename,
+            input_path, output_path, input_mime_type, output_mime_type,
+            error_message, created_at, updated_at, expires_at
+     FROM conversion_jobs WHERE expires_at < NOW()`
+  );
+  return rows.map(toCamelJob);
+}
+
+export async function deleteJob(pool, id) {
+  await pool.query('DELETE FROM conversion_jobs WHERE id = ?', [id]);
+}