feat: run jobs on instance creation when run_on_create is enabled

Jobs with run_on_create=true in their config fire automatically
after a new instance is created. Runs fire-and-forget so they don't
delay the 201 response. Option exposed as a checkbox in each job's
detail panel.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

server/jobs.js

@@ -129,6 +129,13 @@ export async function runJob(jobId) {
 
 const _intervals = new Map();
 
+export async function runJobsOnCreate() {
+  for (const job of getJobs()) {
+    const cfg = JSON.parse(job.config || '{}');
+    if (cfg.run_on_create) runJob(job.id).catch(e => console.error(`runJobsOnCreate job ${job.id}:`, e));
+  }
+}
+
 export function restartJobs() {
   for (const iv of _intervals.values()) clearInterval(iv);
   _intervals.clear();