Improve portable launch, forge persistence, and operator auth UX.

Persist build extra_files for Build Manager history, print dashboard login on every start, add libp2p for Mesh P2P forge, defer WebSocket until login, and split devrun.bat from LAUNCH.bat with USB deck auto-detection.

server/internal/maintenance/retention.go

@@ -1,9 +1,11 @@
 package maintenance
 
 import (
+	"context"
 	"log"
 	"os"
 	"path/filepath"
+	"sync"
 	"time"
 
 	"crypto-miner-server/internal/db"
@@ -15,21 +17,47 @@ var retentionTickInterval = 6 * time.Hour
 // runRetentionFn is the work function invoked by StartRetentionJobs (overridable in tests).
 var runRetentionFn = runRetention
 
+var (
+	retentionMu     sync.Mutex
+	retentionCancel context.CancelFunc
+)
+
 // StartRetentionJobs purges old stats and build artifacts on an interval.
 func StartRetentionJobs(database *db.Database, dataDir string, statsHours, buildDays int) {
 	if statsHours <= 0 && buildDays <= 0 {
 		return
 	}
+	ctx, cancel := context.WithCancel(context.Background())
+	retentionMu.Lock()
+	retentionCancel = cancel
+	retentionMu.Unlock()
+
 	go func() {
 		runRetentionFn(database, dataDir, statsHours, buildDays)
 		ticker := time.NewTicker(retentionTickInterval)
 		defer ticker.Stop()
-		for range ticker.C {
-			runRetentionFn(database, dataDir, statsHours, buildDays)
+		for {
+			select {
+			case <-ctx.Done():
+				return
+			case <-ticker.C:
+				runRetentionFn(database, dataDir, statsHours, buildDays)
+			}
 		}
 	}()
 }
 
+// StopRetentionJobs stops the background retention loop started by StartRetentionJobs.
+func StopRetentionJobs() {
+	retentionMu.Lock()
+	cancel := retentionCancel
+	retentionCancel = nil
+	retentionMu.Unlock()
+	if cancel != nil {
+		cancel()
+	}
+}
+
 func runRetention(database *db.Database, dataDir string, statsHours, buildDays int) {
 	if statsHours > 0 {
 		cutoff := time.Now().Add(-time.Duration(statsHours) * time.Hour)