feat(PROJ-22): LDAP Web-GUI + feat(PROJ-21): Multi-Tenancy Phase 1

PROJ-22 – LDAP Web-GUI Konfiguration & Test:
- internal/ldapconfig/store.go: AES-256-GCM Passwortspeicherung, CRUD Upsert (id=1)
- internal/ldapauth/client.go: TestConnection (RootDSE, UserCount) + Authenticate (2-step bind)
- internal/auth/auth.go: LDAP-Fallback in Login(), Gruppen-Rollenzuordnung, issueToken helper
- internal/api/ldap_tenants.go: GET/PUT/DELETE/POST-test /api/admin/ldap mit Audit-Log
- go.mod: github.com/go-ldap/ldap/v3 v3.4.8 hinzugefügt
- Frontend: LDAPConfig/LDAPTestResult Typen, LDAP-Tab mit Gruppen-Mappings + Testergebnis

PROJ-21 Phase 1+6+7 – Multi-Tenancy Grundstruktur:
- internal/tenantstore/store.go: tenants, tenant_domains, tenant_ldap Schema; Migration users/audit_log
- API: 8 Tenant-Routen (CRUD + Domain-Management) via SetTenants()
- cmd/archivmail/main.go: ldapSt + tenantSt initialisiert
- Frontend: Mandanten-Tab mit Tabelle, Domain-Dialog, Deaktivieren/Löschen

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

cmd/archivmail/main.go

@@ -20,9 +20,11 @@ import (
 	"github.com/archivmail/internal/auth"
 	imapstore "github.com/archivmail/internal/imap"
 	"github.com/archivmail/internal/index"
+	ldapcfg "github.com/archivmail/internal/ldapconfig"
 	pop3store "github.com/archivmail/internal/pop3"
 	"github.com/archivmail/internal/smtpd"
 	"github.com/archivmail/internal/storage"
+	tenantstore "github.com/archivmail/internal/tenantstore"
 	"github.com/archivmail/internal/userstore"
 	"github.com/archivmail/pkg/mailparser"
 )
@@ -121,8 +123,16 @@ func main() {
 		logger.Error("seed users failed", "err", err)
 	}
 
-	// Auth manager
-	authMgr := auth.New(users, nil, cfg.API.Secret)
+	// LDAP config store
+	ldapSt, err := ldapcfg.New(cfg.Database.DSN(), cfg.API.Secret)
+	if err != nil {
+		logger.Error("ldap config store init failed", "err", err)
+		os.Exit(1)
+	}
+	defer ldapSt.Close()
+
+	// Auth manager (with LDAP fallback)
+	authMgr := auth.New(users, ldapSt, cfg.API.Secret)
 
 	// API server
 	apiCfg := config.APIConfig{
@@ -155,6 +165,9 @@ func main() {
 	}
 	defer smtpDaemon.Stop()
 
+	// Wire LDAP config store into API server
+	srv.SetLDAP(ldapSt)
+
 	// Wire SMTP daemon into API server for status endpoint
 	srv.SetSMTPDaemon(smtpDaemon)
 
@@ -171,6 +184,15 @@ func main() {
 	defer imapSched.Stop()
 	srv.SetImap(imapSt, imapImp, imapSched)
 
+	// Tenant store (Multi-Tenancy Phase 1)
+	tenantSt, err := tenantstore.New(cfg.Database.DSN())
+	if err != nil {
+		logger.Error("tenant store init failed", "err", err)
+		os.Exit(1)
+	}
+	defer tenantSt.Close()
+	srv.SetTenants(tenantSt)
+
 	// POP3 store + importer
 	pop3St, err := pop3store.New(cfg.Database.DSN(), cfg.API.Secret)
 	if err != nil {