feat(cli): add --agents-allowed to template commands (#27517)

Relates to CODAGT-713

Depends on #27515

This adds `--agents-allowed` to `coder templates create` and `coder templates edit`. Template creation defaults the option to true, matching the per-template API and database default, while template editing only changes the value when the flag is explicitly supplied so unrelated edits preserve the existing setting.

The generated CLI help and reference documentation include the new option. #27518 updates the Coder Agents platform controls documentation to describe the completed per-template model.

cli/templatecreate.go

@@ -21,6 +21,7 @@ func (r *RootCmd) templateCreate() *serpent.Command {
 		provisionerTags      []string
 		variablesFile        string
 		commandLineVariables []string
+		agentsAllowed        bool
 		disableEveryone      bool
 		requireActiveVersion bool
 
@@ -159,6 +160,7 @@ func (r *RootCmd) templateCreate() *serpent.Command {
 				TimeTilDormantAutoDeleteMillis: ptr.Ref(dormancyAutoDeletion.Milliseconds()),
 				DisableEveryoneGroupAccess:     disableEveryone,
 				RequireActiveVersion:           requireActiveVersion,
+				AgentsAllowed:                  &agentsAllowed,
 			}
 
 			template, err := client.CreateTemplate(inv.Context(), organization.ID, createReq)
@@ -179,6 +181,12 @@ func (r *RootCmd) templateCreate() *serpent.Command {
 		},
 	}
 	cmd.Options = serpent.OptionSet{
+		{
+			Flag:        "agents-allowed",
+			Description: "Allow Coder Agents to create workspaces using this template.",
+			Default:     "true",
+			Value:       serpent.BoolOf(&agentsAllowed),
+		},
 		{
 			Flag: "private",
 			Description: "Disable the default behavior of granting template access to the 'everyone' group. " +