feat(ai): implement intelligent auto-tagging system

- Added multi-provider AI infrastructure (OpenAI/Ollama)
- Implemented real-time tag suggestions with debounced analysis
- Created AI diagnostics and database maintenance tools in Settings
- Added automated garbage collection for orphan labels
- Refined UX with deterministic color hashing and interactive ghost tags

keep-notes/lib/ai/factory.ts

@@ -0,0 +1,25 @@
+import { OpenAIProvider } from './providers/openai';
+import { OllamaProvider } from './providers/ollama';
+import { AIProvider } from './types';
+
+export function getAIProvider(): AIProvider {
+  const providerType = process.env.AI_PROVIDER || 'ollama'; // Default to ollama for local dev
+
+  switch (providerType.toLowerCase()) {
+    case 'ollama':
+      console.log('Using Ollama Provider with model:', process.env.OLLAMA_MODEL || 'granite4:latest');
+      return new OllamaProvider(
+        process.env.OLLAMA_BASE_URL || 'http://localhost:11434/api',
+        process.env.OLLAMA_MODEL || 'granite4:latest'
+      );
+    case 'openai':
+    default:
+      if (!process.env.OPENAI_API_KEY) {
+        console.warn('OPENAI_API_KEY non configurée. Les fonctions IA pourraient échouer.');
+      }
+      return new OpenAIProvider(
+        process.env.OPENAI_API_KEY || '',
+        process.env.OPENAI_MODEL || 'gpt-4o-mini'
+      );
+  }
+}