fix(admin): verify CSRF token in message admin Mods [#139] (#264)

sendMessage, massmessage and sysmessage are POSTed to directly, bypassing
admin.php's central csrf_verify(). Add csrf_verify() (after the admin access
check, via the shared GameEngine/Admin/csrf.php) and csrf_field() in their
forms (Newmessage.tpl, massmessage.tpl, sysmessage.tpl; the mass/sys templates
have both a prepare and an execute form).

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

Admin/Templates/Newmessage.tpl

@@ -54,6 +54,7 @@ $user = $database->getUserArray($id,1);
     </div>
     
     <form method="post" action="../GameEngine/Admin/Mods/sendMessage.php" name="msg">
+      <?php echo csrf_field(); ?>
       <div class="msg-body">
         <input type="hidden" name="uid" value="<?php echo $id; ?>">
         

Admin/Templates/massmessage.tpl

@@ -66,6 +66,7 @@ $_SESSION['mass_color']   = $_SESSION['mass_color'] ?? 'black';
       <b>Subject:</b> <span style="color:<?=$_SESSION['mass_color']?>"><?=htmlspecialchars($_SESSION['mass_subject'])?></span>
     </div>
     <form action="../GameEngine/Admin/Mods/massmessage.php" method="POST" class="massmsg-form">
+      <?php echo csrf_field(); ?>
       <input type="hidden" name="admid" value="<?=$id?>">
       <input type="hidden" name="action" value="execute">
       <button type="submit" name="confirm" value="Yes" style="background:#27ae60">✓ Yes, Send</button>
@@ -80,6 +81,7 @@ $_SESSION['mass_color']   = $_SESSION['mass_color'] ?? 'black';
 
 <?php else:?>
     <form action="../GameEngine/Admin/Mods/massmessage.php" method="POST" class="massmsg-form">
+      <?php echo csrf_field(); ?>
       <input type="hidden" name="admid" value="<?=$id?>">
       <input type="hidden" name="action" value="prepare">
 

Admin/Templates/sysmessage.tpl

@@ -68,6 +68,7 @@ $_SESSION['sys_color']   = $_SESSION['sys_color'] ?? 'black';
     </div>
 
     <form action="../GameEngine/Admin/Mods/sysmessage.php" method="POST" class="sysmsg-form">
+        <?php echo csrf_field(); ?>
         <input type="hidden" name="admid" value="<?=$id?>">
         <input type="hidden" name="action" value="execute">
 
@@ -84,7 +85,7 @@ $_SESSION['sys_color']   = $_SESSION['sys_color'] ?? 'black';
 <?php else: ?>
 
     <form action="../GameEngine/Admin/Mods/sysmessage.php" method="POST" class="sysmsg-form">
-
+        <?php echo csrf_field(); ?>
         <input type="hidden" name="admid" value="<?=$id?>">
         <input type="hidden" name="action" value="prepare">
 

GameEngine/Admin/Mods/massmessage.php

@@ -20,6 +20,11 @@ if (!isset($_SESSION['access']) || $_SESSION['access'] < ADMIN) {
     die("Access Denied");
 }
 
+// Issue #139: this Mod is POSTed to directly, so it must verify the CSRF token
+// itself (it does not go through admin.php's central csrf_verify()).
+require_once(__DIR__ . '/../csrf.php');
+csrf_verify();
+
 /*
 |--------------------------------------------------------------------------
 | PREPARE

GameEngine/Admin/Mods/sendMessage.php

@@ -18,6 +18,11 @@ if (empty($_SESSION['access']) || $_SESSION['access'] < 9) {
     die("Access Denied: You are not Admin!");
 }
 
+// Issue #139: this Mod is POSTed to directly, so it must verify the CSRF token
+// itself (it does not go through admin.php's central csrf_verify()).
+require_once(__DIR__ . '/../csrf.php');
+csrf_verify();
+
 include_once("../../config.php");
 
 // ---------------------------------------------------------------------------

GameEngine/Admin/Mods/sysmessage.php

@@ -24,6 +24,11 @@ if (!isset($_SESSION['access']) || $_SESSION['access'] < ADMIN) {
     die("Access Denied");
 }
 
+// Issue #139: this Mod is POSTed to directly, so it must verify the CSRF token
+// itself (it does not go through admin.php's central csrf_verify()).
+require_once(__DIR__ . '/../csrf.php');
+csrf_verify();
+
 // ---------------------------------------------------------------------------
 // Resolve project root (so we can read/write Templates/*.tpl)
 // ---------------------------------------------------------------------------