feat(ops): alert on filesystem fill levels from the host worker

Add a pure df parser (disk-usage.ts) with 85/90/95% threshold classification, a diskPressure() alert (Discord/email/alert_logs, severity escalates with fill), and a 5-minute host-side probe in jobs-worker.ts that raises one alert per crossing mount, cooldown-gated per mount+level. Real mounts only: overlay/tmpfs pseudo filesystems are ignored.

src/lib/services/alert.test.ts

@@ -24,7 +24,7 @@ vi.mock("@/env", () => ({
 }));
 
 import { sendMail } from "@/lib/services/email";
-import { sendAlert } from "./alert";
+import { diskPressure, sendAlert } from "./alert";
 
 beforeEach(() => {
 	insertValues.mockReset();
@@ -64,3 +64,45 @@ describe("sendAlert", () => {
 		expect(sendMail).not.toHaveBeenCalled();
 	});
 });
+
+describe("diskPressure", () => {
+	const usage = (percent: number) => ({
+		filesystem: "/dev/vda1",
+		mount: "/",
+		totalBytes: 100000000000,
+		usedBytes: (percent / 100) * 100000000000,
+		availableBytes: 100000000000 - (percent / 100) * 100000000000,
+		percent,
+	});
+
+	it("raises a warning at 87% fill", async () => {
+		await diskPressure(usage(87));
+		expect(insertValues).toHaveBeenCalledWith(
+			expect.objectContaining({
+				type: "disk",
+				severity: "warning",
+			}),
+		);
+	});
+
+	it("raises an error at 92% fill", async () => {
+		await diskPressure(usage(92));
+		expect(insertValues).toHaveBeenCalledWith(
+			expect.objectContaining({
+				type: "disk",
+				severity: "error",
+			}),
+		);
+	});
+
+	it("raises a critical alert at 96% fill", async () => {
+		await diskPressure(usage(96));
+		expect(insertValues).toHaveBeenCalledWith(
+			expect.objectContaining({
+				type: "disk",
+				severity: "critical",
+				context: expect.stringContaining('"mount":"/"'),
+			}),
+		);
+	});
+});