feat: multi-provider AI support with auto-detection

- Added support for Google Gemini, OpenAI, Anthropic, and Azure OpenAI
- Implemented API key validation with auto model detection
- Added Error Boundary for better error handling
- Migrated PDF generation to native jsPDF (better quality)
- Added PWA support with offline capabilities
- Implemented tests with Vitest
- Fixed language consistency (PT-BR)
- Improved accessibility (ARIA)

components/Header.tsx

@@ -1,33 +1,55 @@
 import React from 'react';
 import { LogoBase64, SunIcon, MoonIcon, RefreshIcon, SignOutIcon } from './Icons';
 import { useTheme } from '../context/ThemeContext';
+import type { AIProvider } from '../types/providers';
 
 interface HeaderProps {
   onReset: () => void;
   onClearKey: () => void;
   hasKey: boolean;
+  provider?: AIProvider;
 }
 
-export const Header: React.FC<HeaderProps> = ({ onReset, onClearKey, hasKey }) => {
+export const Header: React.FC<HeaderProps> = ({ onReset, onClearKey, hasKey, provider }) => {
   const { theme, toggleTheme } = useTheme();
 
+  const providerColors: Record<AIProvider, string> = {
+    gemini: 'from-blue-500 to-indigo-600',
+    openai: 'from-green-500 to-emerald-600',
+    anthropic: 'from-orange-500 to-amber-600',
+    azure: 'from-blue-600 to-cyan-600'
+  };
+
+  const providerNames: Record<AIProvider, string> = {
+    gemini: 'Gemini',
+    openai: 'OpenAI',
+    anthropic: 'Claude',
+    azure: 'Azure'
+  };
+
   return (
     <header className="sticky top-0 z-30 transition-all duration-300 backdrop-blur-md bg-white/70 dark:bg-slate-900/70 border-b border-white/20 dark:border-slate-800 shadow-sm">
       <div className="container mx-auto px-4 py-3 flex items-center justify-between">
         <div className="flex items-center gap-3">
           <div className="relative group cursor-pointer">
             <div className="absolute -inset-1 bg-gradient-to-r from-blue-600 to-indigo-600 rounded-full blur opacity-25 group-hover:opacity-50 transition duration-1000 group-hover:duration-200"></div>
-            <img src={LogoBase64} alt="SteelBase Logo" className="relative w-10 h-10 object-contain" />
+            <img src={LogoBase64} alt="SteelCheck Logo" className="relative w-10 h-10 object-contain" />
           </div>
 
           <div className="hidden sm:block">
             <h1 className="text-2xl font-display font-bold bg-clip-text text-transparent bg-gradient-to-r from-slate-900 to-slate-700 dark:from-white dark:to-slate-300">
-              SteelBase
+              SteelCheck
             </h1>
           </div>
         </div>
 
         <div className="flex items-center gap-2 sm:gap-4">
+          {hasKey && provider && (
+            <div className={`hidden sm:flex items-center gap-2 px-3 py-1.5 rounded-full bg-gradient-to-r ${providerColors[provider]} text-white text-xs font-medium`}>
+              {providerNames[provider]}
+            </div>
+          )}
+
           {hasKey && (
             <button
               onClick={onClearKey}