fix(daemon): allow read-only daemon commands with Dolt backend

The daemon guard was blocking ALL daemon commands when using Dolt
backend, including read-only commands like `status`, `stop`, `logs`.

Changes:
- Rename guard to `guardDaemonStartForDolt` (more accurate)
- Remove `PersistentPreRunE` from `daemonCmd` and `daemonsCmd`
- Add `PreRunE` guard only to `daemonStartCmd` and `daemonsRestartCmd`
- Update test to use new function name and test start command

Now:
- `bd daemon status` works with Dolt backend
- `bd daemon start` blocked unless `--federation` flag
- `bd daemon start --federation` works (starts dolt sql-server)

Fixes: bd-n7o47

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

cmd/bd/dolt_singleprocess_test.go

@@ -69,7 +69,7 @@ func TestDoltSingleProcess_TryAutoStartDoesNotCreateStartlock(t *testing.T) {
 	}
 }
 
-func TestDoltSingleProcess_DaemonGuardBlocksCommands(t *testing.T) {
+func TestDoltSingleProcess_DaemonGuardBlocksStartCommand(t *testing.T) {
 	oldDBPath := dbPath
 	t.Cleanup(func() { dbPath = oldDBPath })
 	dbPath = ""
@@ -78,12 +78,14 @@ func TestDoltSingleProcess_DaemonGuardBlocksCommands(t *testing.T) {
 	beadsDir, _ := writeDoltWorkspace(t, ws)
 	t.Setenv("BEADS_DIR", beadsDir)
 
-	// Ensure help flag exists (cobra adds it during execution; for unit testing we add it explicitly).
-	cmd := daemonCmd
+	// Use daemonStartCmd which has the guard attached.
+	// Ensure help and federation flags exist (cobra adds them during execution).
+	cmd := daemonStartCmd
 	cmd.Flags().Bool("help", false, "help")
-	err := guardDaemonUnsupportedForDolt(cmd, nil)
+	// Note: federation flag is already registered in init()
+	err := guardDaemonStartForDolt(cmd, nil)
 	if err == nil {
-		t.Fatalf("expected daemon guard error for dolt backend")
+		t.Fatalf("expected daemon guard error for dolt backend without --federation")
 	}
 	if !strings.Contains(err.Error(), "single-process") {
 		t.Fatalf("expected error to mention single-process, got: %v", err)