feat: add user authentication UI to header component

Add login and register dialogs, user dropdown menu with profile link and logout option, and integrate with session management hook. Prevent hydration mismatches by conditionally rendering auth elements after mount. Update package-lock.json with new @esbuild dependencies for build tooling.

messages/en.json

@@ -329,5 +329,77 @@
       "share": "Share with friends",
       "back": "Back to home"
     }
+  },
+  "auth": {
+    "login": {
+      "title": "Sign In",
+      "description": "Sign in to access your account",
+      "emailOrUsername": "Email or Username",
+      "emailOrUsernamePlaceholder": "[email protected] or username",
+      "password": "Password",
+      "passwordPlaceholder": "••••••••",
+      "loginButton": "Sign In",
+      "loggingIn": "Signing in...",
+      "invalidCredentials": "Invalid credentials"
+    },
+    "register": {
+      "title": "Create Account",
+      "description": "Register to start trading",
+      "username": "Username",
+      "usernamePlaceholder": "your_username",
+      "usernameHint": "3-50 characters, letters, numbers and _",
+      "email": "Email",
+      "emailPlaceholder": "[email protected]",
+      "password": "Password",
+      "passwordPlaceholder": "••••••••",
+      "passwordHint": "Min. 8 characters, 1 uppercase, 1 lowercase, 1 number",
+      "confirmPassword": "Confirm Password",
+      "confirmPasswordPlaceholder": "••••••••",
+      "firstName": "First Name",
+      "firstNamePlaceholder": "Your first name",
+      "lastName": "Last Name",
+      "lastNamePlaceholder": "Your last name",
+          "phone": "Phone (optional)",
+          "phonePlaceholder": "(11) 98888-7777",
+          "phoneHint": "Select country and enter phone number",
+          "searchCountry": "Search country...",
+      "servers": "Servers",
+      "serversDescription": "Select the servers where you play",
+      "selectServer": "Select Server",
+      "characterName": "Character Name",
+      "characterNamePlaceholder": "Your character name",
+      "characterNameHint": "Min. 3 characters",
+      "addServer": "Add Server",
+      "removeServer": "Remove",
+      "mainCharacter": "Main Character",
+      "atLeastOneServer": "Select at least one server",
+      "characterRequired": "Character name is required",
+      "submit": "Create Account",
+      "submitting": "Creating account...",
+      "success": "Account created successfully!",
+      "errors": {
+        "emailExists": "This email is already registered",
+        "usernameExists": "This username is already in use",
+        "characterExists": "This character is already registered on this server",
+        "serverNotFound": "Server not found or inactive",
+        "passwordMismatch": "Passwords do not match",
+        "weakPassword": "Password too weak",
+        "invalidEmail": "Invalid email",
+        "invalidPhone": "Invalid phone",
+        "noServers": "Select at least one server",
+        "characterNameRequired": "Character name is required for all selected servers"
+      },
+      "passwordStrength": {
+        "weak": "Weak",
+        "medium": "Medium",
+        "strong": "Strong"
+      },
+      "passwordRequirements": {
+        "minLength": "Minimum 8 characters",
+        "uppercase": "1 uppercase letter",
+        "lowercase": "1 lowercase letter",
+        "number": "1 number"
+      }
+    }
   }
 }