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/ModelSelector.tsx

@@ -0,0 +1,51 @@
+import React, { useState, useEffect } from 'react';
+import { PROVIDERS, type AIProvider } from '../types/providers';
+
+interface ModelSelectorProps {
+  provider: AIProvider;
+  onModelChange: (model: string) => void;
+  apiKey: string;
+}
+
+export const ModelSelector: React.FC<ModelSelectorProps> = ({ provider, onModelChange, apiKey }) => {
+  const [selectedModel, setSelectedModel] = useState<string>('');
+  const providerConfig = PROVIDERS.find(p => p.id === provider);
+
+  useEffect(() => {
+    if (providerConfig) {
+      const saved = localStorage.getItem(`model-${provider}`);
+      if (saved && providerConfig.models.includes(saved)) {
+        setSelectedModel(saved);
+        onModelChange(saved);
+      } else {
+        setSelectedModel(providerConfig.defaultModel);
+        onModelChange(providerConfig.defaultModel);
+      }
+    }
+  }, [provider, providerConfig, onModelChange]);
+
+  const handleChange = (model: string) => {
+    setSelectedModel(model);
+    localStorage.setItem(`model-${provider}`, model);
+    onModelChange(model);
+  };
+
+  if (!providerConfig) return null;
+
+  return (
+    <div>
+      <label className="block text-xs font-semibold text-slate-500 dark:text-slate-400 uppercase tracking-wider mb-2">
+        Modelo
+      </label>
+      <select
+        value={selectedModel}
+        onChange={(e) => handleChange(e.target.value)}
+        className="w-full px-4 py-3 bg-white/50 dark:bg-slate-700/50 border border-slate-300 dark:border-slate-600 rounded-xl shadow-sm focus:outline-none focus:ring-2 focus:ring-blue-500 transition-all text-slate-700 dark:text-slate-200"
+      >
+        {providerConfig.models.map((model) => (
+          <option key={model} value={model}>{model}</option>
+        ))}
+      </select>
+    </div>
+  );
+};