feat: Added LLM factory initialization functionality and knowledge base related API interfaces (#13472)

### What problem does this PR solve?

feat: Added LLM factory initialization functionality and knowledge base
related API interfaces

refactor(dao): Refactored the TenantLLMDAO query method
feat(handler): Implemented knowledge base related API endpoints
feat(service): Added LLM API key setting functionality
feat(model): Extended the knowledge base model definition
feat(config): Added default user LLM configuration

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

cmd/server_main.go

@@ -6,6 +6,7 @@ import (
 	"net/http"
 	"os"
 	"os/signal"
+	"ragflow/internal/init_data"
 	"ragflow/internal/server"
 	"ragflow/internal/utility"
 	"strings"
@@ -71,6 +72,13 @@ func main() {
 		logger.Fatal("Failed to initialize database", zap.Error(err))
 	}
 
+	// Initialize LLM factory data models from configuration file
+	if err := init_data.InitLLMFactory(); err != nil {
+		logger.Error("Failed to initialize LLM factory", err)
+	} else {
+		logger.Info("LLM factory initialized successfully")
+	}
+
 	// Initialize doc engine
 	if err := engine.Init(&cfg.DocEngine); err != nil {
 		logger.Fatal("Failed to initialize doc engine", zap.Error(err))