topology: add bcachefs-2copy; add bcachefs-single; rename single->btrfs-single; update planner, fs mapping, CLI, defaults, preview topo strings, README

src/cli/args.rs

@@ -55,18 +55,22 @@ impl std::fmt::Display for LogLevelArg {
 #[derive(Debug, Clone, Copy, ValueEnum)]
 #[value(rename_all = "kebab_case")]
 pub enum TopologyArg {
-    Single,
+    BtrfsSingle,
+    BcachefsSingle,
     DualIndependent,
     SsdHddBcachefs,
+    Bcachefs2Copy,
     BtrfsRaid1,
 }
 
 impl std::fmt::Display for TopologyArg {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         let s = match self {
-            TopologyArg::Single => "single",
+            TopologyArg::BtrfsSingle => "btrfs_single",
+            TopologyArg::BcachefsSingle => "bcachefs_single",
             TopologyArg::DualIndependent => "dual_independent",
             TopologyArg::SsdHddBcachefs => "ssd_hdd_bcachefs",
+            TopologyArg::Bcachefs2Copy => "bcachefs_2copy",
             TopologyArg::BtrfsRaid1 => "btrfs_raid1",
         };
         f.write_str(s)