feat: add mergerfs mover and snapraid integration

New 'Almacenamiento' page with:
- Auto-detection of rsync, mergerfs, snapraid binaries and mergerfs mount
- Configurable pool settings (source/dest, macOS cleanup, rsync flags)
- Mergerfs mover with dry-run preview and live SSE output streaming
- SnapRAID diff/sync/scrub/check with live SSE output
- Async job system (1 concurrent job) with SSE streaming
- Job history table

Backend:
- internal/storage/ package with capabilities, mergerfs, snapraid, jobs
- storage_config and storage_jobs DB tables (migration 0008)
- GET/PUT /api/storage/config, GET /api/storage/capabilities
- POST/GET /api/storage/jobs, GET /api/storage/jobs/{id}/stream
- Storage operations disabled when NASCTL_EXEC_SYSTEM=false

Closes #new-feature

internal/web/auth.go

@@ -17,6 +17,7 @@ import (
 
 	"github.com/darroyo/nasctl/internal/db"
 	"github.com/darroyo/nasctl/internal/engine"
+	"github.com/darroyo/nasctl/internal/storage"
 )
 
 const (
@@ -199,6 +200,7 @@ type Server struct {
 	AdminUsername  string
 	UploadMaxBytes  int64
 	PreviewMaxBytes int64
+	JM             *storage.JobManager
 }
 
 type Options struct {
@@ -209,6 +211,7 @@ type Options struct {
 	AdminUsername   string
 	UploadMaxBytes  int64
 	PreviewMaxBytes int64
+	JobManager      *storage.JobManager
 }
 
 func NewServer(database *db.DB, eng *engine.Engine, opts Options) *Server {
@@ -228,6 +231,7 @@ func NewServer(database *db.DB, eng *engine.Engine, opts Options) *Server {
 		AdminUsername:  opts.AdminUsername,
 		UploadMaxBytes:  opts.UploadMaxBytes,
 		PreviewMaxBytes: opts.PreviewMaxBytes,
+		JM:             opts.JobManager,
 	}
 }