feat(askcli): add watch subcommand

Implements `ask watch [subcommand...]` which re-runs a read-only
subcommand every 2 seconds and redraws output when it changes,
similar to gnu-watch.

Safety features:
- Restricted to read-only subcommands (list, all, ready, info,
  urgency, help, dep list)
- Recursive watch is blocked
- Captures stderr so error messages are visible in the watched display

Also adds readOnly field to commandEntry registry for maintainability.

1 files changed, 5 insertions, 0 deletions

diff --git a/internal/askcli/dispatch.go b/internal/askcli/dispatch.go
index cd2aae7..2cdaa93 100644
--- a/internal/askcli/dispatch.go
+++ b/internal/askcli/dispatch.go
@@ -54,6 +54,10 @@ func (d *Dispatcher) Dispatch(ctx context.Context, args []string, stdin io.Reade
 	if len(args) == 0 {
 		args = []string{"list"}
 	}
+	return d.dispatchCommand(ctx, args, stdin, stdout, stderr)
+}
+
+func (d *Dispatcher) dispatchCommand(ctx context.Context, args []string, stdin io.Reader, stdout, stderr io.Writer) (int, error) {
 	subcommand := args[0]
 	entry, ok := commandRegistry.get(subcommand)
 	if !ok {
@@ -90,6 +94,7 @@ func (d *Dispatcher) help(w io.Writer) (int, error) {
 	_, _ = io.WriteString(w, "  ask dep rm <id|uuid> <dep>    Remove dependency\n")
 	_, _ = io.WriteString(w, "  ask dep list <id|uuid>        List dependencies\n")
 	_, _ = io.WriteString(w, "  ask urgency                   List tasks sorted by urgency\n")
+	_, _ = io.WriteString(w, "  ask watch [subcommand...]     Re-run a read-only subcommand every 2s and redraw on changes\n")
 	_, _ = io.WriteString(w, "  ask modify <id|uuid> <args...> Modify task fields\n")
 	_, _ = io.WriteString(w, "  ask denotate <id|uuid> \"text\" Remove annotation\n")
 	_, _ = io.WriteString(w, "  ask delete <id|uuid>          Delete a task\n")