feat: AI provider testing page + multi-provider support + UX design spec

- Add AI Provider Testing page (/admin/ai-test) with Tags and Embeddings tests
- Add new AI providers: CustomOpenAI, DeepSeek, OpenRouter
- Add API routes for AI config, models listing, and testing endpoints
- Add UX Design Specification document for Phase 1 MVP AI
- Add PRD Phase 1 MVP AI planning document
- Update admin settings and sidebar navigation
- Fix AI factory for multi-provider support

keep-notes/lib/ai/providers/openai.ts

@@ -1,13 +1,20 @@
-import { openai } from '@ai-sdk/openai';
+import { createOpenAI } from '@ai-sdk/openai';
 import { generateObject, embed } from 'ai';
 import { z } from 'zod';
 import { AIProvider, TagSuggestion } from '../types';
 
 export class OpenAIProvider implements AIProvider {
   private model: any;
+  private embeddingModel: any;
 
-  constructor(apiKey: string, modelName: string = 'gpt-4o-mini') {
-    this.model = openai(modelName);
+  constructor(apiKey: string, modelName: string = 'gpt-4o-mini', embeddingModelName: string = 'text-embedding-3-small') {
+    // Create OpenAI client with API key
+    const openaiClient = createOpenAI({
+      apiKey: apiKey,
+    });
+
+    this.model = openaiClient(modelName);
+    this.embeddingModel = openaiClient.embedding(embeddingModelName);
   }
 
   async generateTags(content: string): Promise<TagSuggestion[]> {
@@ -20,7 +27,7 @@ export class OpenAIProvider implements AIProvider {
             confidence: z.number().min(0).max(1).describe('Le niveau de confiance entre 0 et 1')
           }))
         }),
-        prompt: `Analyse la note suivante et suggère entre 1 et 5 tags pertinents. 
+        prompt: `Analyse la note suivante et suggère entre 1 et 5 tags pertinents.
         Contenu de la note: "${content}"`,
       });
 
@@ -34,7 +41,7 @@ export class OpenAIProvider implements AIProvider {
   async getEmbeddings(text: string): Promise<number[]> {
     try {
       const { embedding } = await embed({
-        model: openai.embedding('text-embedding-3-small'),
+        model: this.embeddingModel,
         value: text,
       });
       return embedding;