v0.4.0: monitoring & backup — scheduler, CPU/temp metrics, healthchecks, restic backups

Phase 2 (Monitoring & Health):
- Central job scheduler replacing ad-hoc goroutines (internal/scheduler)
- CPU usage collector via /proc/stat background sampling (internal/system/cpu_linux.go)
- Temperature reading from /sys/class/thermal + /host/sys (Docker mount)
- Load average from /proc/loadavg
- Healthchecks.io-compatible HTTP pinger (internal/monitor/pinger.go)
- System health checks: disk, memory, CPU, temp, Docker, protected containers (internal/monitor/healthcheck.go)

Phase 3 (Backups):
- Database auto-discovery via docker ps + docker inspect (internal/backup/dbdump.go)
- Database dumping via docker exec (pg_dump / mariadb-dump) with atomic writes
- Restic backup integration with auto-password generation (internal/backup/restic.go)
- Backup orchestrator: DB dumps + restic snapshots + weekly prune (internal/backup/backup.go)
- Manual backup trigger via dashboard button and POST /api/backup/run

Dashboard UI:
- CPU usage bar with load average display
- Temperature with colored indicator dot
- Backup status card with last run time, DB count, repo stats
- "Mentés most" button for manual backup trigger

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

controller/internal/web/templates/style.css

@@ -1122,6 +1122,62 @@ select.form-control option { background: var(--bg-secondary); color: var(--text-
     justify-content: flex-end;
 }
 
+/* Load average text */
+.system-load-avg {
+    font-size: .7rem;
+    color: var(--text-muted);
+    font-family: 'JetBrains Mono', monospace;
+    margin-top: .25rem;
+}
+
+/* Temperature dot */
+.temp-dot {
+    display: inline-block;
+    width: 8px;
+    height: 8px;
+    border-radius: 50%;
+    margin-right: .25rem;
+    vertical-align: middle;
+}
+.temp-dot-green { background: var(--green); box-shadow: 0 0 4px rgba(35, 134, 54, 0.5); }
+.temp-dot-yellow { background: var(--yellow); box-shadow: 0 0 4px rgba(210, 153, 34, 0.5); }
+.temp-dot-red { background: var(--red); box-shadow: 0 0 4px rgba(218, 54, 51, 0.5); }
+
+.system-info-item-compact {
+    flex: 0 1 auto;
+    min-width: 120px;
+}
+
+/* Backup status card */
+.backup-status-card {
+    background: var(--bg-card);
+    border-radius: var(--radius);
+    padding: 1rem 1.25rem;
+    border: 1px solid var(--border-color);
+    margin-bottom: 2rem;
+}
+.backup-status-card h3 {
+    margin-bottom: .75rem;
+}
+.backup-info-row {
+    display: flex;
+    justify-content: space-between;
+    align-items: center;
+    padding: .25rem 0;
+    font-size: .85rem;
+}
+.backup-label {
+    color: var(--text-secondary);
+}
+.backup-value {
+    color: var(--text-primary);
+    font-family: 'JetBrains Mono', monospace;
+    font-size: .8rem;
+}
+.backup-status-ok { color: var(--green); }
+.backup-status-fail { color: var(--red); }
+.backup-status-none { color: var(--text-muted); }
+
 /* Responsive */
 @media(max-width: 768px) {
     .sidebar { width: 100%; height: auto; position: relative; border-right: none; border-bottom: 1px solid var(--border-color); }