Show memory and disk capacity (used/total) on dashboard tiles

Previously the Mem/Disk bars only showed a percentage. Plumbed the
underlying byte totals through the whole stack -- collectors, DB
(with a migration for the already-deployed CT122 instance), API, and
the web tile -- so each card also shows e.g. "19.6/32.0 GB".

Verified end-to-end with a throwaway local instance (seeded snapshot,
logged in, screenshotted the rendered tile).

Note: the SSH-collected hosts (omv, ripper) assume the remote
monitor-readonly.sh script emits raw bytes for MEMLINE/DISK_, matching
Proxmox's convention -- unverified since that script only lives on
those two hosts, not in this repo.

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

apps/api/src/db/index.ts

@@ -29,6 +29,10 @@ export function openDb(path: string): Database.Database {
       cpu_pct REAL,
       mem_pct REAL,
       disk_pct REAL,
+      mem_total_bytes REAL,
+      mem_used_bytes REAL,
+      disk_total_bytes REAL,
+      disk_used_bytes REAL,
       mem_pressure_pct REAL,
       cpu_pressure_pct REAL,
       uptime_sec INTEGER,
@@ -70,6 +74,15 @@ export function openDb(path: string): Database.Database {
       is_bootstrap INTEGER NOT NULL DEFAULT 0
     );
   `);
+  // Migration for metric_snapshots pre-dating the raw byte capacity columns
+  // (CREATE TABLE IF NOT EXISTS above doesn't touch already-existing tables).
+  const snapshotColumns = (db.pragma("table_info(metric_snapshots)") as { name: string }[]).map(
+    (c) => c.name
+  );
+  for (const col of ["mem_total_bytes", "mem_used_bytes", "disk_total_bytes", "disk_used_bytes"]) {
+    if (!snapshotColumns.includes(col)) db.exec(`ALTER TABLE metric_snapshots ADD COLUMN ${col} REAL`);
+  }
+
   // Migration for the devices table pre-dating mdns_hostname (CREATE TABLE IF
   // NOT EXISTS above doesn't touch already-existing tables). SQLite's ALTER
   // TABLE ADD COLUMN has no IF NOT EXISTS clause (unlike CREATE TABLE/INDEX),
@@ -103,9 +116,11 @@ export function upsertSnapshots(db: Database.Database, snapshots: MetricSnapshot
   `);
   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)
+      (host_id, status, cpu_pct, mem_pct, disk_pct, mem_total_bytes, mem_used_bytes,
+       disk_total_bytes, disk_used_bytes, mem_pressure_pct, cpu_pressure_pct, uptime_sec, meta_json)
     VALUES
-      (@hostId, @status, @cpuPct, @memPct, @diskPct, @memPressurePct, @cpuPressurePct, @uptimeSec, @metaJson)
+      (@hostId, @status, @cpuPct, @memPct, @diskPct, @memTotalBytes, @memUsedBytes,
+       @diskTotalBytes, @diskUsedBytes, @memPressurePct, @cpuPressurePct, @uptimeSec, @metaJson)
   `);
 
   const tx = db.transaction((items: MetricSnapshot[]) => {
@@ -125,6 +140,10 @@ export interface LatestRow {
   cpu_pct: number | null;
   mem_pct: number | null;
   disk_pct: number | null;
+  mem_total_bytes: number | null;
+  mem_used_bytes: number | null;
+  disk_total_bytes: number | null;
+  disk_used_bytes: number | null;
   mem_pressure_pct: number | null;
   cpu_pressure_pct: number | null;
   uptime_sec: number | null;
@@ -136,7 +155,8 @@ export function getLatestSnapshots(db: Database.Database): LatestRow[] {
     .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
+             s.disk_pct, s.mem_total_bytes, s.mem_used_bytes, s.disk_total_bytes, s.disk_used_bytes,
+             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 = (