can now only join when in registration period and added test users

backend_splatournament_manager/dist/csv/tournaments.csv

@@ -1,4 +1,4 @@
 name,description,maxTeamAmount,currentTeamAmount,registrationStartDate,registrationEndDate
-Demo Tournament  ,This is a demo tournament, 6, 0, 2026-02-01, 2026-02-28
-Demo Tournament 2,This is a second demo tournament, 12, 5, 2026-03-01, 2026-03-15
-Demo Tournament 3,This is a third demo tournament, 8, 8, 2026-03-10, 2026-03-20
+Demo Tournament  ,This is a demo tournament, 2, 0, 2026-02-01, 2026-02-28
+Demo Tournament 2,This is a second demo tournament, 4, 5, 2026-03-01, 2026-03-15
+Demo Tournament 3,This is a third demo tournament, 8, 8, 2026-03-15, 2026-03-20

backend_splatournament_manager/dist/csv/users.csv

@@ -1,2 +1,6 @@
 username, password
 tikaiz, htlgkr
+test01, htlgkr
+test02, htlgkr
+test03, htlgkr
+test04, htlgkr

docs/prompt.md

@@ -91,3 +91,7 @@ Folgende Dateien wurden in diesem Prompt verändert:
 - In the Teams view, fix the upper TabBar text so selected and non-selected labels are readable.<br><br>
 Folgende Dateien wurden in diesem Prompt verändert:
     - frontend_splatournament_manager/lib/pages/home_page.dart
+
+- Only allow entering a tournament if the registration period is open currently.<br><br>
+Folgende Dateien wurden in diesem Prompt verändert:
+    - frontend_splatournament_manager/lib/pages/tournament_detail_page.dart

frontend_splatournament_manager/lib/pages/tournament_detail_page.dart

@@ -155,10 +155,16 @@ class _TournamentDetailPageState extends State<TournamentDetailPage> {
             child: Padding(
               padding: const EdgeInsets.fromLTRB(12, 0, 12, 24),
               child: ElevatedButton(
-                child: Text("Join with Team"),
-                onPressed: () {
-                  _showJoinTeamDialog(context, widget.tournament.id);
-                },
+                onPressed: widget.tournament.isRegistrationOpen
+                    ? () => _showJoinTeamDialog(context, widget.tournament.id)
+                    : null,
+                child: Text(
+                  widget.tournament.isRegistrationFuture
+                      ? "Registration not open yet"
+                      : widget.tournament.isRegistrationPast
+                      ? "Registration closed"
+                      : "Join with Team",
+                ),
               ),
             ),
           ),