feat(telegram): add AI agent bot with streaming and account context

- Add Telegram bot with long-polling and AI agent loop (api_call tool)
- SSE streaming with real-time message editing and ⏳ placeholder
- Account state injection at conversation start (models, exchanges,
  strategies, traders, per-trader PnL and statistics)
- Lane semaphore per chat serializes concurrent messages (60s timeout)
- Idle timeout watchdog (60s) prevents hung streaming connections
- Look-ahead buffer prevents partial <api_call> tag leaking to user
- Fix PUT /strategies/:id to merge config (read-then-merge pattern)
- Add route registry with full API schema for LLM documentation
- Add TelegramConfig store and Web UI config modal
- Add GetAnyEnabled to AIModel store for bot LLM client selection

store/ai_model.go

@@ -137,6 +137,19 @@ func (s *AIModelStore) firstEnabled(userID string) (*AIModel, error) {
 	return &model, nil
 }
 
+// GetAnyEnabled returns the first enabled AI model across all users.
+// Used by single-user features (e.g. Telegram bot) that need any working LLM client.
+func (s *AIModelStore) GetAnyEnabled() (*AIModel, error) {
+	var model AIModel
+	err := s.db.Where("enabled = ? AND api_key != ''", true).
+		Order("updated_at DESC, id ASC").
+		First(&model).Error
+	if err != nil {
+		return nil, err
+	}
+	return &model, nil
+}
+
 // Update updates AI model, creates if not exists
 // IMPORTANT: If apiKey is empty string, the existing API key will be preserved (not overwritten)
 func (s *AIModelStore) Update(userID, id string, enabled bool, apiKey, customAPIURL, customModelName string) error {