feat: Add AI settings to database (provider/model configurable via UI)

- ai_provider and ai_model stored in settings table
- Editable via /settings page in admin UI
- API keys remain in env vars for security
- Falls back to env vars if settings not in DB

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

backend/migrations/064_ai_settings.sql

@@ -0,0 +1,8 @@
+-- Add AI provider settings to settings table
+-- API keys remain in environment variables for security
+
+INSERT INTO settings (key, value, description, updated_at)
+VALUES
+  ('ai_provider', 'claude', 'AI provider for content generation (claude or openai)', NOW()),
+  ('ai_model', '', 'AI model to use (leave blank for default: gpt-4o for openai, claude-sonnet-4-20250514 for claude)', NOW())
+ON CONFLICT (key) DO NOTHING;

backend/src/services/seoGenerator.ts

@@ -203,15 +203,12 @@ Focus on the business value of cannabis market intelligence.`;
 /**
  * Call Claude API
  */
-async function callClaudeAPI(prompt: string): Promise<GeneratedSeoPayload> {
+async function callClaudeAPI(prompt: string, model: string): Promise<GeneratedSeoPayload> {
   const apiKey = process.env.ANTHROPIC_API_KEY;
   if (!apiKey) {
     throw new Error('ANTHROPIC_API_KEY not configured');
   }
 
-  const model = process.env.AI_MODEL || 'claude-sonnet-4-20250514';
-  console.log(`[SEO] Using Claude model: ${model}`);
-
   const response = await fetch('https://api.anthropic.com/v1/messages', {
     method: 'POST',
     headers: {
@@ -250,15 +247,12 @@ async function callClaudeAPI(prompt: string): Promise<GeneratedSeoPayload> {
 /**
  * Call OpenAI API
  */
-async function callOpenAIAPI(prompt: string): Promise<GeneratedSeoPayload> {
+async function callOpenAIAPI(prompt: string, model: string): Promise<GeneratedSeoPayload> {
   const apiKey = process.env.OPENAI_API_KEY;
   if (!apiKey) {
     throw new Error('OPENAI_API_KEY not configured');
   }
 
-  const model = process.env.AI_MODEL || 'gpt-4o';
-  console.log(`[SEO] Using OpenAI model: ${model}`);
-
   const response = await fetch('https://api.openai.com/v1/chat/completions', {
     method: 'POST',
     headers: {
@@ -296,19 +290,50 @@ async function callOpenAIAPI(prompt: string): Promise<GeneratedSeoPayload> {
   return JSON.parse(jsonMatch[0]);
 }
 
+/**
+ * Get AI settings from database (with env var fallback)
+ */
+async function getAISettings(): Promise<{ provider: string; model: string }> {
+  const pool = getPool();
+
+  let provider = process.env.AI_PROVIDER || 'claude';
+  let model = process.env.AI_MODEL || '';
+
+  try {
+    const result = await pool.query(`
+      SELECT key, value FROM settings
+      WHERE key IN ('ai_provider', 'ai_model')
+    `);
+
+    for (const row of result.rows) {
+      if (row.key === 'ai_provider' && row.value) provider = row.value;
+      if (row.key === 'ai_model' && row.value) model = row.value;
+    }
+  } catch (e) {
+    // Settings table may not exist, use env vars
+  }
+
+  // Default models if not specified
+  if (!model) {
+    model = provider === 'openai' ? 'gpt-4o' : 'claude-sonnet-4-20250514';
+  }
+
+  return { provider, model };
+}
+
 /**
  * Generate SEO content using configured AI provider
  */
 async function generateWithAI(spec: GenerationSpec): Promise<GeneratedSeoPayload> {
-  const provider = process.env.AI_PROVIDER || 'claude';
+  const { provider, model } = await getAISettings();
   const prompt = buildSeoPrompt(spec);
 
-  console.log(`[SEO] Generating content with ${provider} for ${spec.type}: ${spec.slug}`);
+  console.log(`[SEO] Generating content with ${provider} (${model}) for ${spec.type}: ${spec.slug}`);
 
   if (provider === 'openai') {
-    return callOpenAIAPI(prompt);
+    return callOpenAIAPI(prompt, model);
   } else {
-    return callClaudeAPI(prompt);
+    return callClaudeAPI(prompt, model);
   }
 }