Scaffold homelab-monitor: Fastify API + React dashboard + CI

Vertical slice for Phase 1 (v1-dashboard milestone): Proxmox collector,
SQLite storage, local auth, and a dashboard UI showing host/container
status cards. Config-driven collector registry so future data sources
(SSH-based hosts, Zabbix, network discovery) plug in without rewiring.

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

apps/api/src/db/index.ts

@@ -0,0 +1,102 @@
+import Database from "better-sqlite3";
+import { mkdirSync } from "node:fs";
+import { dirname } from "node:path";
+import type { MetricSnapshot } from "../collectors/types.js";
+
+export function openDb(path: string): Database.Database {
+  mkdirSync(dirname(path), { recursive: true });
+  const db = new Database(path);
+  db.pragma("journal_mode = WAL");
+  db.exec(`
+    CREATE TABLE IF NOT EXISTS users (
+      id INTEGER PRIMARY KEY AUTOINCREMENT,
+      username TEXT UNIQUE NOT NULL,
+      password_hash TEXT NOT NULL,
+      created_at TEXT NOT NULL DEFAULT (datetime('now'))
+    );
+
+    CREATE TABLE IF NOT EXISTS hosts (
+      host_id TEXT PRIMARY KEY,
+      display_name TEXT NOT NULL,
+      group_name TEXT NOT NULL
+    );
+
+    CREATE TABLE IF NOT EXISTS metric_snapshots (
+      id INTEGER PRIMARY KEY AUTOINCREMENT,
+      host_id TEXT NOT NULL,
+      ts TEXT NOT NULL DEFAULT (datetime('now')),
+      status TEXT NOT NULL,
+      cpu_pct REAL,
+      mem_pct REAL,
+      disk_pct REAL,
+      mem_pressure_pct REAL,
+      cpu_pressure_pct REAL,
+      uptime_sec INTEGER,
+      meta_json TEXT
+    );
+
+    CREATE INDEX IF NOT EXISTS idx_snapshots_host_ts ON metric_snapshots(host_id, ts);
+  `);
+  return db;
+}
+
+export function upsertSnapshots(db: Database.Database, snapshots: MetricSnapshot[]): void {
+  const upsertHost = db.prepare(`
+    INSERT INTO hosts (host_id, display_name, group_name)
+    VALUES (@hostId, @displayName, @group)
+    ON CONFLICT(host_id) DO UPDATE SET display_name = excluded.display_name, group_name = excluded.group_name
+  `);
+  const insertSnapshot = db.prepare(`
+    INSERT INTO metric_snapshots
+      (host_id, status, cpu_pct, mem_pct, disk_pct, mem_pressure_pct, cpu_pressure_pct, uptime_sec, meta_json)
+    VALUES
+      (@hostId, @status, @cpuPct, @memPct, @diskPct, @memPressurePct, @cpuPressurePct, @uptimeSec, @metaJson)
+  `);
+
+  const tx = db.transaction((items: MetricSnapshot[]) => {
+    for (const s of items) {
+      upsertHost.run(s);
+      insertSnapshot.run({ ...s, metaJson: JSON.stringify(s.meta) });
+    }
+  });
+  tx(snapshots);
+}
+
+export interface LatestRow {
+  host_id: string;
+  display_name: string;
+  group_name: string;
+  status: string;
+  cpu_pct: number | null;
+  mem_pct: number | null;
+  disk_pct: number | null;
+  mem_pressure_pct: number | null;
+  cpu_pressure_pct: number | null;
+  uptime_sec: number | null;
+  ts: string;
+}
+
+export function getLatestSnapshots(db: Database.Database): LatestRow[] {
+  return db
+    .prepare(
+      `
+      SELECT h.host_id, h.display_name, h.group_name, s.status, s.cpu_pct, s.mem_pct,
+             s.disk_pct, s.mem_pressure_pct, s.cpu_pressure_pct, s.uptime_sec, s.ts
+      FROM hosts h
+      JOIN metric_snapshots s ON s.host_id = h.host_id
+      WHERE s.id = (
+        SELECT id FROM metric_snapshots s2 WHERE s2.host_id = h.host_id ORDER BY s2.id DESC LIMIT 1
+      )
+      ORDER BY h.group_name, h.display_name
+    `
+    )
+    .all() as LatestRow[];
+}
+
+// Old snapshots aren't useful yet (no charting in Phase 1) and would grow unbounded
+// on a poll-every-30s cadence, so trim anything older than the retention window.
+export function pruneOldSnapshots(db: Database.Database, retentionHours: number): void {
+  db.prepare(`DELETE FROM metric_snapshots WHERE ts < datetime('now', @cutoff)`).run({
+    cutoff: `-${retentionHours} hours`,
+  });
+}