feat(cli): promote tasks commands from experimental to GA (#20916)

## Overview

This change promotes the tasks CLI commands from `coder exp task` to
`coder task`, marking them as generally available (GA).

## Migration

Users will need to update their scripts from:

```shell
coder exp task create "my task"
```

To:
```shell
coder task create "my task"
```

---

🤖 This change was written by Claude Sonnet 4.5 Thinking using [mux](https://github.com/coder/mux) and reviewed by a human 🏄🏻‍♂️

cli/task_create.go

@@ -0,0 +1,237 @@
+package cli
+
+import (
+	"fmt"
+	"io"
+	"strings"
+
+	"github.com/google/uuid"
+	"golang.org/x/xerrors"
+
+	"github.com/coder/coder/v2/cli/cliui"
+	"github.com/coder/coder/v2/codersdk"
+	"github.com/coder/serpent"
+)
+
+func (r *RootCmd) taskCreate() *serpent.Command {
+	var (
+		orgContext = NewOrganizationContext()
+
+		ownerArg            string
+		taskName            string
+		templateName        string
+		templateVersionName string
+		presetName          string
+		stdin               bool
+		quiet               bool
+	)
+
+	cmd := &serpent.Command{
+		Use:   "create [input]",
+		Short: "Create a task",
+		Long: FormatExamples(
+			Example{
+				Description: "Create a task with direct input",
+				Command:     "coder task create \"Add authentication to the user service\"",
+			},
+			Example{
+				Description: "Create a task with stdin input",
+				Command:     "echo \"Add authentication to the user service\" | coder task create",
+			},
+			Example{
+				Description: "Create a task with a specific name",
+				Command:     "coder task create --name task1 \"Add authentication to the user service\"",
+			},
+			Example{
+				Description: "Create a task from a specific template / preset",
+				Command:     "coder task create --template backend-dev --preset \"My Preset\" \"Add authentication to the user service\"",
+			},
+			Example{
+				Description: "Create a task for another user (requires appropriate permissions)",
+				Command:     "coder task create --owner user@example.com \"Add authentication to the user service\"",
+			},
+		),
+		Middleware: serpent.Chain(
+			serpent.RequireRangeArgs(0, 1),
+		),
+		Options: serpent.OptionSet{
+			{
+				Name:        "name",
+				Flag:        "name",
+				Description: "Specify the name of the task. If you do not specify one, a name will be generated for you.",
+				Value:       serpent.StringOf(&taskName),
+				Required:    false,
+				Default:     "",
+			},
+			{
+				Name:        "owner",
+				Flag:        "owner",
+				Description: "Specify the owner of the task. Defaults to the current user.",
+				Value:       serpent.StringOf(&ownerArg),
+				Required:    false,
+				Default:     codersdk.Me,
+			},
+			{
+				Name:  "template",
+				Flag:  "template",
+				Env:   "CODER_TASK_TEMPLATE_NAME",
+				Value: serpent.StringOf(&templateName),
+			},
+			{
+				Name:  "template-version",
+				Flag:  "template-version",
+				Env:   "CODER_TASK_TEMPLATE_VERSION",
+				Value: serpent.StringOf(&templateVersionName),
+			},
+			{
+				Name:    "preset",
+				Flag:    "preset",
+				Env:     "CODER_TASK_PRESET_NAME",
+				Value:   serpent.StringOf(&presetName),
+				Default: PresetNone,
+			},
+			{
+				Name:        "stdin",
+				Flag:        "stdin",
+				Description: "Reads from stdin for the task input.",
+				Value:       serpent.BoolOf(&stdin),
+			},
+			{
+				Name:          "quiet",
+				Flag:          "quiet",
+				FlagShorthand: "q",
+				Description:   "Only display the created task's ID.",
+				Value:         serpent.BoolOf(&quiet),
+			},
+		},
+		Handler: func(inv *serpent.Invocation) error {
+			client, err := r.InitClient(inv)
+			if err != nil {
+				return err
+			}
+
+			var (
+				ctx       = inv.Context()
+				expClient = codersdk.NewExperimentalClient(client)
+
+				taskInput               string
+				templateVersionID       uuid.UUID
+				templateVersionPresetID uuid.UUID
+			)
+
+			organization, err := orgContext.Selected(inv, client)
+			if err != nil {
+				return xerrors.Errorf("get current organization: %w", err)
+			}
+
+			if stdin {
+				bytes, err := io.ReadAll(inv.Stdin)
+				if err != nil {
+					return xerrors.Errorf("reading stdin: %w", err)
+				}
+
+				taskInput = string(bytes)
+			} else {
+				if len(inv.Args) != 1 {
+					return xerrors.Errorf("expected an input for task")
+				}
+
+				taskInput = inv.Args[0]
+			}
+
+			if taskInput == "" {
+				return xerrors.Errorf("a task cannot be started with an empty input")
+			}
+
+			switch {
+			case templateName == "":
+				templates, err := client.Templates(ctx, codersdk.TemplateFilter{SearchQuery: "has-ai-task:true", OrganizationID: organization.ID})
+				if err != nil {
+					return xerrors.Errorf("list templates: %w", err)
+				}
+
+				if len(templates) == 0 {
+					return xerrors.Errorf("no task templates configured")
+				}
+
+				// When a deployment has only 1 AI task template, we will
+				// allow omitting the template. Otherwise we will require
+				// the user to be explicit with their choice of template.
+				if len(templates) > 1 {
+					templateNames := make([]string, 0, len(templates))
+					for _, template := range templates {
+						templateNames = append(templateNames, template.Name)
+					}
+
+					return xerrors.Errorf("template name not provided, available templates: %s", strings.Join(templateNames, ", "))
+				}
+
+				if templateVersionName != "" {
+					templateVersion, err := client.TemplateVersionByOrganizationAndName(ctx, organization.ID, templates[0].Name, templateVersionName)
+					if err != nil {
+						return xerrors.Errorf("get template version: %w", err)
+					}
+
+					templateVersionID = templateVersion.ID
+				} else {
+					templateVersionID = templates[0].ActiveVersionID
+				}
+
+			case templateVersionName != "":
+				templateVersion, err := client.TemplateVersionByOrganizationAndName(ctx, organization.ID, templateName, templateVersionName)
+				if err != nil {
+					return xerrors.Errorf("get template version: %w", err)
+				}
+
+				templateVersionID = templateVersion.ID
+
+			default:
+				template, err := client.TemplateByName(ctx, organization.ID, templateName)
+				if err != nil {
+					return xerrors.Errorf("get template: %w", err)
+				}
+
+				templateVersionID = template.ActiveVersionID
+			}
+
+			if presetName != PresetNone {
+				templatePresets, err := client.TemplateVersionPresets(ctx, templateVersionID)
+				if err != nil {
+					return xerrors.Errorf("get template presets: %w", err)
+				}
+
+				preset, err := resolvePreset(templatePresets, presetName)
+				if err != nil {
+					return xerrors.Errorf("resolve preset: %w", err)
+				}
+
+				templateVersionPresetID = preset.ID
+			}
+
+			task, err := expClient.CreateTask(ctx, ownerArg, codersdk.CreateTaskRequest{
+				Name:                    taskName,
+				TemplateVersionID:       templateVersionID,
+				TemplateVersionPresetID: templateVersionPresetID,
+				Input:                   taskInput,
+			})
+			if err != nil {
+				return xerrors.Errorf("create task: %w", err)
+			}
+
+			if quiet {
+				_, _ = fmt.Fprintln(inv.Stdout, task.ID)
+			} else {
+				_, _ = fmt.Fprintf(
+					inv.Stdout,
+					"The task %s has been created at %s!\n",
+					cliui.Keyword(task.Name),
+					cliui.Timestamp(task.CreatedAt),
+				)
+			}
+
+			return nil
+		},
+	}
+	orgContext.AttachOptions(cmd)
+	return cmd
+}