Move fleet retention and concurrency controls into Settings

Persist settings in SQLite, import legacy environment values once, and apply changes to cleanup and deployment queues without restarting.

Closes #51

src/lib/server/pipeline/sweep.ts

@@ -1,4 +1,4 @@
-import { config } from '../config.js';
+import { fleetSettings } from '../settings.js';
 import { db } from '../db/index.js';
 import { emit } from './bus.js';
 import { requestRestart } from '../provisioning/index.js';
@@ -44,7 +44,7 @@ async function runSweep(): Promise<SweepResult> {
     db().prepare(`DELETE FROM deployments WHERE started_at < ?
         AND NOT EXISTS (SELECT 1 FROM watchdog_actions WHERE campaign_id = deployments.id) AND NOT EXISTS (
         SELECT 1 FROM deployment_servers WHERE deployment_id = deployments.id AND restart_state IN ('pending','failed','held'))`)
-        .run(new Date(Date.now() - config.deployKeepDays * 86_400_000).toISOString());
+        .run(new Date(Date.now() - fleetSettings().deployKeepDays * 86_400_000).toISOString());
     emit({ type: 'sweep-tick', frozen: false });
     return result;
 }