fix: make paragraph refactor service use configured AI provider

The paragraph-refactor service was using OLLAMA_BASE_URL directly from
environment variables instead of using the configured AI provider from
the database. This caused "OLLAMA error" even when OpenAI was configured
in the admin interface.

Changes:
- paragraph-refactor.service.ts: Now uses getSystemConfig() and
  getTagsProvider() from factory instead of direct Ollama calls
- factory.ts: Added proper error messages when API keys are missing
- .env.docker.example: Updated with new provider configuration
  variables (AI_PROVIDER_TAGS, AI_PROVIDER_EMBEDDING)

This fixes the issue where AI reformulation features (Clarify, Shorten,
Improve Style) would fail with OLLAMA errors even when OpenAI was
properly configured in the admin settings.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

keep-notes/lib/ai/services/paragraph-refactor.service.ts

@@ -7,6 +7,8 @@
  */
 
 import { LanguageDetectionService } from './language-detection.service'
+import { getTagsProvider } from '../factory'
+import { getSystemConfig } from '@/lib/config'
 
 export type RefactorMode = 'clarify' | 'shorten' | 'improveStyle'
 
@@ -83,37 +85,13 @@ export class ParagraphRefactorService {
       const systemPrompt = this.getSystemPrompt(mode)
       const userPrompt = this.getUserPrompt(mode, content, language)
 
-      // Get AI provider response using fetch
-      let baseUrl = process.env.OLLAMA_BASE_URL
+      // Get AI provider from factory
+      const config = await getSystemConfig()
+      const provider = getTagsProvider(config)
 
-      if (!baseUrl) {
-        throw new Error('OLLAMA_BASE_URL environment variable is required')
-      }
-
-      // Remove /api suffix if present to avoid double /api/api/...
-      if (baseUrl.endsWith('/api')) {
-        baseUrl = baseUrl.slice(0, -4)
-      }
-      const modelName = process.env.OLLAMA_MODEL || 'granite4:latest'
-
-      const response = await fetch(`${baseUrl}/api/generate`, {
-        method: 'POST',
-        headers: { 'Content-Type': 'application/json' },
-        body: JSON.stringify({
-          model: modelName,
-          system: systemPrompt,
-          prompt: userPrompt,
-          stream: false,
-        }),
-      })
-
-      if (!response.ok) {
-        throw new Error(`Provider error: ${response.statusText}`)
-      }
-
-      const data = await response.json()
-
-      const refactored = this.extractRefactoredText(data.response)
+      // Use provider's generateText method
+      const fullPrompt = `${systemPrompt}\n\n${userPrompt}`
+      const refactored = await provider.generateText(fullPrompt)
 
       // Calculate word count change
       const refactoredWordCount = refactored.split(/\s+/).length
@@ -189,38 +167,16 @@ ${content}
 Original language: ${language}
 IMPORTANT: Provide all 3 versions in ${language}. No English, no explanations.`
 
-      // Get AI provider response using fetch
-      let baseUrl = process.env.OLLAMA_BASE_URL
+      // Get AI provider from factory
+      const config = await getSystemConfig()
+      const provider = getTagsProvider(config)
 
-      if (!baseUrl) {
-        throw new Error('OLLAMA_BASE_URL environment variable is required')
-      }
-
-      // Remove /api suffix if present to avoid double /api/api/...
-      if (baseUrl.endsWith('/api')) {
-        baseUrl = baseUrl.slice(0, -4)
-      }
-      const modelName = process.env.OLLAMA_MODEL || 'granite4:latest'
-
-      const response = await fetch(`${baseUrl}/api/generate`, {
-        method: 'POST',
-        headers: { 'Content-Type': 'application/json' },
-        body: JSON.stringify({
-          model: modelName,
-          system: systemPrompt,
-          prompt: userPrompt,
-          stream: false,
-        }),
-      })
-
-      if (!response.ok) {
-        throw new Error(`Provider error: ${response.statusText}`)
-      }
-
-      const data = await response.json()
+      // Use provider's generateText method
+      const fullPrompt = `${systemPrompt}\n\n${userPrompt}`
+      const response = await provider.generateText(fullPrompt)
 
       // Parse JSON response
-      const jsonResponse = JSON.parse(data.response)
+      const jsonResponse = JSON.parse(response)
 
       const modes: RefactorMode[] = ['clarify', 'shorten', 'improveStyle']
       const results: RefactorResult[] = []