Add i18n support for French and German with browser language detection

templates/login.html

@@ -1,19 +1,19 @@
 {% extends "base.html" %}
-{% block title %}Login — Meal Tracker{% endblock %}
+{% block title %}{{ t('Login — Meal Tracker') }}{% endblock %}
 {% block content %}
 <div class="form-card">
-    <h2>Log In</h2>
+    <h2>{{ t('Log In') }}</h2>
     <form method="POST">
-        <label for="username">Username</label>
+        <label for="username">{{ t('Username') }}</label>
         <input type="text" id="username" name="username" required autofocus>
 
-        <label for="password">Password</label>
+        <label for="password">{{ t('Password') }}</label>
         <input type="password" id="password" name="password" required>
 
-        <button type="submit" class="btn btn-primary">Log In</button>
+        <button type="submit" class="btn btn-primary">{{ t('Log In') }}</button>
     </form>
     <p class="form-footer">
-        Don't have an account? <a href="{{ url_for('auth.register') }}">Register</a>
+        {{ t("Don't have an account?") }} <a href="{{ url_for('auth.register') }}">{{ t('Register') }}</a>
     </p>
 </div>
 {% endblock %}