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/config/config.go

@@ -89,11 +89,12 @@ type RetentionConfig struct {
 }
 
 type MonitoringConfig struct {
-	Enabled             bool             `yaml:"enabled"`
-	HealthchecksBase    string           `yaml:"healthchecks_base"`
-	PingUUIDs           PingUUIDsConfig  `yaml:"ping_uuids"`
-	HealthCheckSchedule string           `yaml:"health_check_schedule"`
-	Thresholds          ThresholdsConfig `yaml:"thresholds"`
+	Enabled              bool             `yaml:"enabled"`
+	HealthchecksBase     string           `yaml:"healthchecks_base"`
+	PingUUIDs            PingUUIDsConfig  `yaml:"ping_uuids"`
+	HealthCheckSchedule  string           `yaml:"health_check_schedule"`
+	SystemHealthInterval string           `yaml:"system_health_interval"`
+	Thresholds           ThresholdsConfig `yaml:"thresholds"`
 }
 
 type PingUUIDsConfig struct {
@@ -187,8 +188,10 @@ func applyDefaults(cfg *Config) {
 	di(&cfg.Backup.Retention.KeepDaily, 7)
 	di(&cfg.Backup.Retention.KeepWeekly, 4)
 	di(&cfg.Backup.Retention.KeepMonthly, 6)
+	d(&cfg.Backup.ResticPasswordFile, "/opt/docker/felhom-controller/data/restic-password")
 	d(&cfg.Monitoring.HealthchecksBase, "https://status.felhom.eu")
 	d(&cfg.Monitoring.HealthCheckSchedule, "06:00")
+	d(&cfg.Monitoring.SystemHealthInterval, "5m")
 	di(&cfg.Monitoring.Thresholds.DiskWarnPercent, 80)
 	di(&cfg.Monitoring.Thresholds.DiskCritPercent, 90)
 	di(&cfg.Monitoring.Thresholds.BackupMaxAgeHours, 36)
@@ -217,6 +220,7 @@ func applyEnvOverrides(cfg *Config) {
 	envStr("FELHOM_PATHS_STACKS_DIR", &cfg.Paths.StacksDir)
 	envStr("FELHOM_PATHS_HDD_PATH", &cfg.Paths.HDDPath)
 	envStr("FELHOM_LOGGING_LEVEL", &cfg.Logging.Level)
+	envStr("FELHOM_MONITORING_SYSTEM_HEALTH_INTERVAL", &cfg.Monitoring.SystemHealthInterval)
 }
 
 func validate(cfg *Config) error {