fix: use rag.description viper key and add CLI config fallback for --desc

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: tae2089

cmd/ccg/main.go

@@ -157,7 +157,7 @@ func runServe(deps *cli.Deps, cfg cli.ServeConfig) error {
 		Logger:            deps.Logger,
 		Cache:             cache,
 		RagIndexDir:       viper.GetString("rag.index_dir"),
-		RagProjectDesc:    viper.GetString("description"),
+		RagProjectDesc:    viper.GetString("rag.description"),
 	}
 
 	srv := mcpserver.NewServer(mcpDeps)

internal/cli/ragindex.go

@@ -7,6 +7,7 @@ import (
 	"strings"
 
 	"github.com/spf13/cobra"
+	"github.com/spf13/viper"
 
 	"github.com/imtaebin/code-context-graph/internal/ragindex"
 )
@@ -25,6 +26,11 @@ func newRagIndexCmd(deps *Deps) *cobra.Command {
 				return fmt.Errorf("database not initialized")
 			}
 
+			// --desc 플래그가 없으면 viper config에서 읽음
+			if projectDesc == "" {
+				projectDesc = viper.GetString("rag.description")
+			}
+
 			b := &ragindex.Builder{
 				DB:          deps.DB,
 				OutDir:      resolveOutDir(outDir),