Integrate Monolog: replace four logging systems with single PSR-3 factory

- Add monolog/monolog dependency (^3.10)  
- Create app/Logger.php central factory with channels: app, admin, error, audit
- Each channel gets RotatingFileHandler (30-day retention) with pass-through LineFormatter
  preserving existing JSON format contracts
- Rewrite AppLogger as thin facade delegating to Logger::get('app')
- Rewrite ErrorHandler::log() to delegate to Logger::get('error')
- Rewrite AdminLogger file output to delegate to Logger::get('admin'), keep DB writes
- Add Monolog file shadow to Audit via Logger::get('audit') (Option A per monolog-plan)
- Log level controlled by LOG_LEVEL env var (defaults: DEBUG in cli-server, WARNING otherwise)
- Graceful NullHandler fallback when log directory is not writable
- Update SystemController LOG_FILES: remove php_error, add app/admin/error/audit
- JSON app logs parsed to readable one-liners in the log viewer
- Remove nginx config tab (parametres + fragment + template + css)
- Friendly empty-state message when app log files don't exist yet (notYet)
- PHP tail fallback when exec() unavailable
- All 228 PHPUnit tests pass, no call sites changed

app/templates/admin/partials/system-log-panel.php

@@ -19,7 +19,7 @@
 
 <?php if ($logFileMeta): ?>
 <div class="log-meta">
-    <span data-label="Fichier"><?= htmlspecialchars(SystemController::LOG_FILES[$activeTab]['path']) ?></span>
+    <span data-label="Fichier"><?= htmlspecialchars($logFileMeta['path']) ?></span>
     <span data-label="Taille"><?= $logFileMeta['size'] ?></span>
     <span data-label="Modifié"><?= $logFileMeta['mtime'] ?></span>
 </div>
@@ -29,7 +29,7 @@
     <div class="log-unavailable">
         <strong>Journaux non disponibles</strong>
         <div class="log-unavail-path"><?= $logError ?></div>
-        <?php if (php_sapi_name() === 'cli-server'): ?>
+        <?php if (php_sapi_name() === 'cli-server' && str_starts_with($activeTab, 'nginx')): ?>
         <div class="log-unavail-dev">
             En environnement de développement, les logs nginx ne sont pas disponibles.
             Cette page est pleinement fonctionnelle sur le serveur de production.
@@ -37,6 +37,12 @@
         <?php endif; ?>
     </div>
 
+<?php elseif (!empty($notYet)): ?>
+    <div class="log-empty">
+        Aucune entrée pour le moment.<br>
+        <span class="log-unavail-path">Le journal sera créé automatiquement au premier événement.</span>
+    </div>
+
 <?php elseif (empty($logLines)): ?>
     <div class="log-empty">Le fichier journal est vide.</div>
 

app/templates/admin/partials/system-nginx-config-panel.php

@@ -1,40 +0,0 @@
-<?php if ($nginxConfigMeta): ?>
-<div class="log-meta">
-    <span data-label="Fichier"><?= htmlspecialchars($nginxConfigMeta['path']) ?></span>
-    <span data-label="Taille"><?= $nginxConfigMeta['size'] ?></span>
-    <span data-label="Modifié"><?= $nginxConfigMeta['mtime'] ?></span>
-    <?php if ($nginxConfigSource === 'live'): ?>
-    <span class="nginx-source-badge nginx-source-badge--live">● Config déployée</span>
-    <?php else: ?>
-    <span class="nginx-source-badge nginx-source-badge--local">⚠ Référence locale (config live inaccessible)</span>
-    <?php endif; ?>
-</div>
-<?php endif; ?>
-
-<?php if ($nginxConfigError !== null): ?>
-    <div class="log-unavailable">
-        <strong>Configuration nginx non disponible</strong>
-        <div class="log-unavail-path"><?= htmlspecialchars($nginxConfigError) ?></div>
-        <?php if (php_sapi_name() === 'cli-server'): ?>
-        <div class="log-unavail-dev">
-            En développement, <code>/etc/nginx/sites-available/xamxam</code> n'existe pas.
-            La config de référence se trouve dans <code>nginx/xamxam.conf</code>.
-        </div>
-        <?php endif; ?>
-    </div>
-
-<?php elseif (empty($nginxConfigLines)): ?>
-    <div class="log-empty">Le fichier de configuration est vide.</div>
-
-<?php else: ?>
-    <div class="log-output" id="log-output" role="region" aria-label="Configuration nginx">
-        <button class="btn btn--secondary btn--sm log-copy-btn" id="log-copy-btn" type="button" title="Copier la configuration"
-                onclick="copyLogContent(this);return false">
-            Copier
-        </button>
-        <?php foreach ($nginxConfigLines as $i => $line): ?>
-        <span class="log-line <?= SystemController::nginxLineClass($line) ?>"
-              data-n="<?= $i + 1 ?>"><?= htmlspecialchars($line, ENT_QUOTES | ENT_SUBSTITUTE) ?></span>
-        <?php endforeach; ?>
-    </div>
-<?php endif; ?>