Add i18n translations for page content (Home, Database, Logs)

Extended internationalization support by adding translation keys and data-i18n attributes to page content. Previously only the sidebar was translated - now the main content of Home, Database, and Logs pages will switch between French and English when the user changes the language selector.

Translation keys added:
- Home page: title, welcome message, PM measures, Linux stats, disk/memory usage
- Database page: all UI labels, buttons, and dropdown options
- Logs page: title, description, log types, and action buttons

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

html/index.html

@@ -51,16 +51,16 @@
         </aside>
       <!-- Main content -->
       <main class="col-md-9 ms-sm-auto col-lg-10 offset-md-3 offset-lg-2 px-md-4">
-        <h1 class="mt-4">Votre capteur</h1>
-        <p>Bienvenue sur votre interface de configuration de votre capteur.</p>
-        
+        <h1 class="mt-4" data-i18n="home.title">Votre capteur</h1>
+        <p data-i18n="home.welcome">Bienvenue sur votre interface de configuration de votre capteur.</p>
+
         <div class="row mb-3">
 
           <!-- Card  NPM values -->
           <div class="col-sm-4 mt-2">
-          <div class="card"> 
+          <div class="card">
             <div class="card-body">
-              <h5 class="card-title">Mesures PM</h5>
+              <h5 class="card-title" data-i18n="home.pmMeasures">Mesures PM</h5>
               <canvas id="sensorPMChart" style="width: 100%; max-width: 600px; height: 200px;"></canvas>
             </div>
           </div>
@@ -68,14 +68,14 @@
 
           <!-- Card  Linux Stats -->
           <div class="col-sm-4 mt-2">
-            <div class="card"> 
+            <div class="card">
               <div class="card-body">
-                <h5 class="card-title">Linux stats</h5>
-                <p class="card-text">Disk usage (total size <span id="disk_size"></span> Gb) </p>
+                <h5 class="card-title" data-i18n="home.linuxStats">Statistiques Linux</h5>
+                <p class="card-text"><span data-i18n="home.diskUsage">Utilisation du disque (taille totale</span> <span id="disk_size"></span> Gb) </p>
                 <div id="disk_space"></div>
-                <p class="card-text">Memory usage (total size <span id="memory_size"></span> Mb) </p>
+                <p class="card-text"><span data-i18n="home.memoryUsage">Utilisation de la mémoire (taille totale</span> <span id="memory_size"></span> Mb) </p>
                 <div id="memory_space"></div>
-                <p class="card-text"> Database size: <span id="database_size"></span> </p>
+                <p class="card-text"><span data-i18n="home.databaseSize">Taille de la base de données:</span> <span id="database_size"></span> </p>
               </div>
             </div>
           </div>