feat(backup): pg_dump + state-tarball + daily auto + UI

Production-Box braucht Backups — bisher keine. Jetzt komplette
Pipeline:

Backend (internal/services/backup/):
  - Output: /var/backups/edgeguard/eg-YYYYMMDD-HHMMSS.tar.gz
  - Inhalt: dump.sql (pg_dump --clean --if-exists --no-owner --no-acl),
    files/setup.json, files/license_key, files/license.cache,
    files/.jwt_fingerprint, files/node.conf, files/acme-account/* +
    manifest.json (Version, kind, hostname, sizes)
  - sha256 während-write via TeeWriter, Size + sha in backups-DB-Row
  - Failure-Path: row mit status=failed + error, kein orphan-tarball
  - Prune(keepN=14) löscht erfolgreiche Backups älter als die letzten N

Migration 0018: backups(id, file, size, sha256, db/files bytes, kind,
status, error, host, started/finished).

Scheduler (cmd/edgeguard-scheduler):
  - 24h-Tick → backup.Run(KindScheduled) + Prune. Beim Boot wird ein
    initialer Backup NICHT sofort gezogen (kein nervöses Spam),
    sondern erst beim nächsten 24h-Slot.

REST (internal/handlers/backup.go):
  GET    /api/v1/backups              — list (newest first)
  POST   /api/v1/backups              — trigger manual (sync, audit'ed)
  GET    /api/v1/backups/:id          — single
  GET    /api/v1/backups/:id/download — sendfile tar.gz
  DELETE /api/v1/backups/:id          — entferne file + row

UI (management-ui/src/pages/Backups):
  - Liste mit Time, File+sha (first 16), Kind-Tag, Status, Size (mit
    DB + Files Aufschlüsselung), Dauer
  - „Backup jetzt erstellen" Button, Refresh, Download, Delete
  - Auto-Refresh 30s
  - Sidebar-Eintrag „Backups" unter System

postinst:
  - /var/backups/edgeguard 0750 edgeguard:edgeguard (enthält sensitive
    pg_dump + license_key → NICHT world-readable)
  - sudoers-Whitelist `sudo -u postgres /usr/bin/pg_dump --clean
    --if-exists --no-owner --no-acl edgeguard` — exakte Form

Verifiziert auf der Box: backups-Tabelle existiert, scheduler logged
„backup enabled tick=24h dir=/var/backups/edgeguard keep_n=14",
pg_dump-via-sudoers liefert 2808 lines.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

cmd/edgeguard-scheduler/main.go

@@ -18,13 +18,14 @@ import (
 	"git.netcell-it.de/projekte/edgeguard-native/internal/database"
 	"git.netcell-it.de/projekte/edgeguard-native/internal/license"
 	"git.netcell-it.de/projekte/edgeguard-native/internal/services/acme"
+	"git.netcell-it.de/projekte/edgeguard-native/internal/services/backup"
 	"git.netcell-it.de/projekte/edgeguard-native/internal/services/certrenewer"
 	licsvc "git.netcell-it.de/projekte/edgeguard-native/internal/services/license"
 	"git.netcell-it.de/projekte/edgeguard-native/internal/services/setup"
 	"git.netcell-it.de/projekte/edgeguard-native/internal/services/tlscerts"
 )
 
-var version = "1.0.63"
+var version = "1.0.64"
 
 const (
 	// renewTickInterval — how often we re-evaluate expiring certs.
@@ -39,6 +40,11 @@ const (
 	// licenseTickInterval — daily re-verify against
 	// license.netcell-it.com. Result lands in the licenses table.
 	licenseTickInterval = 24 * time.Hour
+
+	// backupTickInterval — daily scheduled backup at ~03:00 (Tick
+	// alignment ist approximativ, weil time.Ticker bei Boot startet).
+	// Retention: 14 erfolgreiche Backups (default in backup.Service).
+	backupTickInterval = 24 * time.Hour
 )
 
 func main() {
@@ -74,6 +80,10 @@ func main() {
 	nodeID := os.Getenv("EDGEGUARD_NODE_ID")
 	slog.Info("scheduler: license re-verify enabled", "tick", licenseTickInterval)
 
+	backupSvc := backup.New(pool)
+	slog.Info("scheduler: daily backup enabled", "tick", backupTickInterval,
+		"dir", backupSvc.BackupDir, "keep_n", backup.DefaultKeepN)
+
 	if renewer != nil {
 		runRenewer(ctx, renewer)
 	}
@@ -83,6 +93,8 @@ func main() {
 	defer renewTick.Stop()
 	licTick := time.NewTicker(licenseTickInterval)
 	defer licTick.Stop()
+	backupTick := time.NewTicker(backupTickInterval)
+	defer backupTick.Stop()
 
 	for {
 		select {
@@ -92,10 +104,29 @@ func main() {
 			}
 		case <-licTick.C:
 			runLicenseVerify(ctx, licClient, licKeyStore, licRepo, nodeID)
+		case <-backupTick.C:
+			runBackup(ctx, backupSvc, version)
 		}
 	}
 }
 
+// runBackup führt einen scheduled Backup aus + prunet alte. Failures
+// loggen wir nur — der Tick läuft morgen wieder, kein Notfall.
+func runBackup(ctx context.Context, svc *backup.Service, version string) {
+	res, err := svc.Run(ctx, backup.KindScheduled, version)
+	if err != nil {
+		slog.Warn("scheduler: backup failed", "error", err, "file", res.File)
+		return
+	}
+	slog.Info("scheduler: backup done",
+		"file", res.File, "size", res.SizeBytes,
+		"db_bytes", res.DBDumpBytes, "files_bytes", res.FilesBytes,
+		"sha256", res.SHA256)
+	if err := svc.Prune(ctx, backup.DefaultKeepN); err != nil {
+		slog.Warn("scheduler: backup prune failed", "error", err)
+	}
+}
+
 // runLicenseVerify performs a single re-verify pass. Empty key = no-op
 // (box stays in trial), so this is safe to call on every tick.
 func runLicenseVerify(ctx context.Context, c *license.Client, ks *license.KeyStore,