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/lang/fr.json

@@ -60,5 +60,42 @@
     "map": "Carte",
     "terminal": "Terminal",
     "admin": "Admin"
+  },
+  "home": {
+    "title": "Votre capteur",
+    "welcome": "Bienvenue sur votre interface de configuration de votre capteur.",
+    "pmMeasures": "Mesures PM",
+    "linuxStats": "Statistiques Linux",
+    "diskUsage": "Utilisation du disque (taille totale",
+    "memoryUsage": "Utilisation de la mémoire (taille totale",
+    "databaseSize": "Taille de la base de données:"
+  },
+  "database": {
+    "title": "Base de données",
+    "description": "Le capteur enregistre en local les données de mesures. Vous pouvez ici les consulter et les télécharger.",
+    "viewDatabase": "Consulter la base de donnée",
+    "numberOfMeasures": "Nombre de mesures:",
+    "last10": "10 dernières",
+    "last20": "20 dernières",
+    "last30": "30 dernières",
+    "pmMeasures": "Mesures PM",
+    "tempHumMeasures": "Mesures Temp/Hum",
+    "pm5Channels": "Mesures PM (5 canaux)",
+    "cairsensProbe": "Sonde Cairsens",
+    "noiseProbe": "Sonde bruit",
+    "windProbe": "Sonde Vent",
+    "battery": "Batterie",
+    "timestampTable": "Timestamp Table",
+    "downloadData": "Télécharger les données",
+    "startDate": "Date de début:",
+    "endDate": "Date de fin:"
+  },
+  "logs": {
+    "title": "Le journal",
+    "description": "Le journal des logs permet de savoir si les processus du capteur se déroulent correctement.",
+    "saraLogs": "Sara logs",
+    "bootLogs": "Boot logs",
+    "refresh": "Refresh",
+    "clear": "Clear"
   }
 }