feat(cmd): add ask option to commands

Add an `ask` attribute to commands that shows a y/n confirmation
before executing. If the user declines, the command is skipped but
the task continues with the next command.

Example:
```yaml
cmds:
  - cmd: echo "Deploying..."
    ask: "Deploy to production?"
  - task: run-migrations
    ask: "Run database migrations?"
```

Behavior:
- Default: asks for y/n confirmation
- --yes: auto-confirms all asks
- --dry: shows commands without asking

This differs from task-level `prompt:` which cancels the entire task
if declined. Command-level `ask:` only skips the individual command.

taskfile/ast/cmd.go

@@ -20,6 +20,7 @@ type Cmd struct {
 	IgnoreError bool
 	Defer       bool
 	Platforms   []*Platform
+	Ask      string
 }
 
 func (c *Cmd) DeepCopy() *Cmd {
@@ -38,6 +39,7 @@ func (c *Cmd) DeepCopy() *Cmd {
 		IgnoreError: c.IgnoreError,
 		Defer:       c.Defer,
 		Platforms:   deepcopy.Slice(c.Platforms),
+		Ask:      c.Ask,
 	}
 }
 
@@ -65,6 +67,7 @@ func (c *Cmd) UnmarshalYAML(node *yaml.Node) error {
 			IgnoreError bool `yaml:"ignore_error"`
 			Defer       *Defer
 			Platforms   []*Platform
+			Ask      string
 		}
 		if err := node.Decode(&cmdStruct); err != nil {
 			return errors.NewTaskfileDecodeError(err, node)
@@ -98,6 +101,7 @@ func (c *Cmd) UnmarshalYAML(node *yaml.Node) error {
 			c.If = cmdStruct.If
 			c.Silent = cmdStruct.Silent
 			c.IgnoreError = cmdStruct.IgnoreError
+			c.Ask = cmdStruct.Ask
 			return nil
 		}
 
@@ -111,6 +115,7 @@ func (c *Cmd) UnmarshalYAML(node *yaml.Node) error {
 			c.Shopt = cmdStruct.Shopt
 			c.IgnoreError = cmdStruct.IgnoreError
 			c.Platforms = cmdStruct.Platforms
+			c.Ask = cmdStruct.Ask
 			return nil
 		}