feat: jobs system with dedicated nav page and run history

Replaces ad-hoc Tailscale config tracking with a proper jobs system.
Jobs get their own nav page (master/detail layout), a dedicated DB
table, and full run history persisted forever. Tailscale connection
settings move from the Settings modal into the Jobs page. Registry
pattern makes adding future jobs straightforward.

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

server/db.js

@@ -17,7 +17,7 @@ function init(path) {
   db.exec('PRAGMA foreign_keys = ON');
   db.exec('PRAGMA synchronous = NORMAL');
   createSchema();
-  if (path !== ':memory:') seed();
+  if (path !== ':memory:') { seed(); seedJobs(); }
 }
 
 function createSchema() {
@@ -58,6 +58,26 @@ function createSchema() {
       key   TEXT PRIMARY KEY,
       value TEXT NOT NULL DEFAULT ''
     );
+
+    CREATE TABLE IF NOT EXISTS jobs (
+      id          INTEGER PRIMARY KEY AUTOINCREMENT,
+      key         TEXT NOT NULL UNIQUE,
+      name        TEXT NOT NULL,
+      description TEXT NOT NULL DEFAULT '',
+      enabled     INTEGER NOT NULL DEFAULT 0 CHECK(enabled IN (0,1)),
+      schedule    INTEGER NOT NULL DEFAULT 15,
+      config      TEXT NOT NULL DEFAULT '{}'
+    );
+
+    CREATE TABLE IF NOT EXISTS job_runs (
+      id         INTEGER PRIMARY KEY AUTOINCREMENT,
+      job_id     INTEGER NOT NULL,
+      started_at TEXT NOT NULL DEFAULT (datetime('now')),
+      ended_at   TEXT,
+      status     TEXT NOT NULL DEFAULT 'running' CHECK(status IN ('running','success','error')),
+      result     TEXT NOT NULL DEFAULT ''
+    );
+    CREATE INDEX IF NOT EXISTS idx_job_runs_job_id ON job_runs(job_id);
   `);
 }
 
@@ -88,6 +108,21 @@ function seed() {
   db.exec('COMMIT');
 }
 
+function seedJobs() {
+  const count = db.prepare('SELECT COUNT(*) as n FROM jobs').get().n;
+  if (count > 0) return;
+  const apiKey   = getConfig('tailscale_api_key');
+  const tailnet  = getConfig('tailscale_tailnet');
+  const schedule = parseInt(getConfig('tailscale_poll_minutes', '15'), 10) || 15;
+  const enabled  = getConfig('tailscale_enabled') === '1' ? 1 : 0;
+  db.prepare(`
+    INSERT INTO jobs (key, name, description, enabled, schedule, config)
+    VALUES ('tailscale_sync', 'Tailscale Sync',
+      'Syncs Tailscale device status and IPs to instances by matching hostnames.',
+      ?, ?, ?)
+  `).run(enabled, schedule, JSON.stringify({ api_key: apiKey, tailnet }));
+}
+
 // ── Queries ───────────────────────────────────────────────────────────────────
 
 export function getInstances(filters = {}) {
@@ -204,6 +239,54 @@ export function setConfig(key, value) {
   ).run(key, String(value));
 }
 
+// ── Jobs ──────────────────────────────────────────────────────────────────────
+
+const JOB_WITH_LAST_RUN = `
+  SELECT j.*,
+    r.id         AS last_run_id,
+    r.started_at AS last_run_at,
+    r.status     AS last_status,
+    r.result     AS last_result
+  FROM jobs j
+  LEFT JOIN job_runs r
+    ON r.id = (SELECT id FROM job_runs WHERE job_id = j.id ORDER BY id DESC LIMIT 1)
+`;
+
+export function getJobs() {
+  return db.prepare(JOB_WITH_LAST_RUN + ' ORDER BY j.id').all();
+}
+
+export function getJob(id) {
+  return db.prepare(JOB_WITH_LAST_RUN + ' WHERE j.id = ?').get(id) ?? null;
+}
+
+export function createJob(data) {
+  db.prepare(`
+    INSERT INTO jobs (key, name, description, enabled, schedule, config)
+    VALUES (@key, @name, @description, @enabled, @schedule, @config)
+  `).run(data);
+}
+
+export function updateJob(id, { enabled, schedule, config }) {
+  db.prepare(`
+    UPDATE jobs SET enabled=@enabled, schedule=@schedule, config=@config WHERE id=@id
+  `).run({ id, enabled, schedule, config });
+}
+
+export function createJobRun(jobId) {
+  return Number(db.prepare('INSERT INTO job_runs (job_id) VALUES (?)').run(jobId).lastInsertRowid);
+}
+
+export function completeJobRun(runId, status, result) {
+  db.prepare(`
+    UPDATE job_runs SET ended_at=datetime('now'), status=@status, result=@result WHERE id=@id
+  `).run({ id: runId, status, result });
+}
+
+export function getJobRuns(jobId) {
+  return db.prepare('SELECT * FROM job_runs WHERE job_id = ? ORDER BY id DESC').all(jobId);
+}
+
 // ── Test helpers ──────────────────────────────────────────────────────────────
 
 export function _resetForTest() {