feat(cli): add pipe support to stop, start, delete, and ls commands (#283)

* feat(cli): add pipe support to stop, start, delete, and ls commands

Add stdin piping and improved output for CLI composability.

Stop/Start/Delete:
- Accept instance names from stdin (one per line)
- Accept multiple instance names as arguments
- Output instance names when piped for chaining
- Add --all flag to stop command

Ls improvements:
- Add --json flag for JSON output
- Output plain table when piped (for grep/awk)
- Add JSON and pipe support to ls orgs

Examples:
  brev ls | awk '/RUNNING/ {print $1}' | brev stop
  brev ls | grep "test-" | awk '{print $1}' | brev delete
  brev ls --json | jq '.[] | select(.status == "RUNNING")'
  brev stop --all

* refactor: extract helper functions to reduce cognitive complexity

- Extract trackLsAnalytics() in ls.go
- Extract runBatchStart() and runSingleStart() in start.go

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

* refactor: extract piping utilities to shared pkg/cmd/util/piping.go

- Consolidate duplicate isStdoutPiped() from delete, ls, start, stop
- Consolidate duplicate getInstanceNames() from delete, stop
- Consolidate duplicate getInstanceNamesFromStdin() from start
- Create IsStdoutPiped(), IsStdinPiped(), GetInstanceNames(), GetInstanceNamesWithPipeInfo()
- Remove ~108 lines of duplicated code

* fix: address PR review comments for piping-composability

- Return errors from runBatchStart instead of silently swallowing them
- Remove unused Piped field from StartOptions
- Add scanner.Err() check after stdin scan loop in piping.go

* feat: add exit code support for partial batch failures

- Add ExitCodeError type to distinguish failure modes
- Batch start returns exit code 2 for partial failure, 1 for all failed
- main.go propagates custom exit codes from ExitCodeError

* feat: add exit code support for partial batch failures in stop

* fix: only pipe output to stdout on full success

Address drewmalin's review: don't send names to stdout when there are
partial failures, since the next piped command would act on them even
without pipefail. Also send admin delete message to stderr instead of
stdout, and remove unused ExitCodeError type.

---------

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Author: theFong

pkg/cmd/delete/delete.go

@@ -3,6 +3,7 @@ package delete
 import (
 	_ "embed"
 	"fmt"
+	"os"
 	"strings"
 
 	"github.com/brevdev/brev-cli/pkg/cmd/completions"
@@ -18,7 +19,7 @@ import (
 var (
 	//go:embed doc.md
 	deleteLong    string
-	deleteExample = "brev delete <ws_name>"
+	deleteExample = "brev delete <ws_name>...\necho instance-name | brev delete"
 )
 
 type DeleteStore interface {
@@ -37,27 +38,41 @@ func NewCmdDelete(t *terminal.Terminal, loginDeleteStore DeleteStore, noLoginDel
 		Example:               deleteExample,
 		ValidArgsFunction:     completions.GetAllWorkspaceNameCompletionHandler(noLoginDeleteStore, t),
 		RunE: func(cmd *cobra.Command, args []string) error {
+			piped := util.IsStdoutPiped()
+			names, err := util.GetInstanceNames(args)
+			if err != nil {
+				return breverrors.WrapAndTrace(err)
+			}
 			var allError error
-			for _, workspace := range args {
-				err := deleteWorkspace(workspace, t, loginDeleteStore)
+			var deletedNames []string
+			for _, workspace := range names {
+				err := deleteWorkspace(workspace, t, loginDeleteStore, piped)
 				if err != nil {
 					allError = multierror.Append(allError, err)
+				} else {
+					deletedNames = append(deletedNames, workspace)
 				}
 			}
 			if allError != nil {
 				return breverrors.WrapAndTrace(allError)
 			}
+			// Only output names for piping if all succeeded
+			if piped {
+				for _, name := range deletedNames {
+					fmt.Println(name)
+				}
+			}
 			return nil
 		},
 	}
 
 	return cmd
 }
 
-func deleteWorkspace(workspaceName string, t *terminal.Terminal, deleteStore DeleteStore) error {
+func deleteWorkspace(workspaceName string, t *terminal.Terminal, deleteStore DeleteStore, piped bool) error {
 	workspace, err := util.GetUserWorkspaceByNameOrIDErr(deleteStore, workspaceName)
 	if err != nil {
-		err1 := handleAdminUser(err, deleteStore)
+		err1 := handleAdminUser(err, deleteStore, piped)
 		if err1 != nil {
 			return breverrors.WrapAndTrace(err1)
 		}
@@ -75,12 +90,14 @@ func deleteWorkspace(workspaceName string, t *terminal.Terminal, deleteStore Del
 		return breverrors.WrapAndTrace(err)
 	}
 
-	t.Vprintf("Deleting instance %s. This can take a few minutes. Run 'brev ls' to check status\n", deletedWorkspace.Name)
+	if !piped {
+		t.Vprintf("Deleting instance %s. This can take a few minutes. Run 'brev ls' to check status\n", deletedWorkspace.Name)
+	}
 
 	return nil
 }
 
-func handleAdminUser(err error, deleteStore DeleteStore) error {
+func handleAdminUser(err error, deleteStore DeleteStore, piped bool) error {
 	if strings.Contains(err.Error(), "not found") {
 		user, err1 := deleteStore.GetCurrentUser()
 		if err1 != nil {
@@ -89,7 +106,9 @@ func handleAdminUser(err error, deleteStore DeleteStore) error {
 		if user.GlobalUserType != "Admin" {
 			return breverrors.WrapAndTrace(err)
 		}
-		fmt.Println("attempting to delete an instance you don't own as admin")
+		if !piped {
+			fmt.Fprintln(os.Stderr, "attempting to delete an instance you don't own as admin")
+		}
 		return nil
 	}