refactor: simplify db and cmd flags, reduce code duplication

- Abstract property flags into addPropertyFlags in cmd/root.go and apply to commands
- Remove unused GetUserByUsername from db.go (it's redundant with service.resolveUserIDByName)
- Use configured user in WithMentions directly in inbox command
- Refactor resolve methods in node_service_sqlite.go to reduce duplication

cmd/list.go

@@ -10,7 +10,7 @@ import (
 	"github.com/spf13/cobra"
 )
 
-var lDummy, lAssignee string
+var lAssignee string
 var lTags []string
 
 var listCmd = &cobra.Command{
@@ -32,11 +32,8 @@ var listCmd = &cobra.Command{
 
 func init() {
 	rootCmd.AddCommand(listCmd)
+	addPropertyFlags(listCmd)
 	f := listCmd.Flags()
-	f.StringVar(&lDummy, "type", "", "")
-	f.StringVar(&lDummy, "status", "", "")
-	f.StringVar(&lDummy, "prio", "", "")
-	f.StringVar(&lDummy, "namespace", "", "")
 	f.StringVar(&lAssignee, "assignee", "", "")
 	f.StringArrayVar(&lTags, "tag", nil, "")
 }