feat(app): report mutations on stderr and say what --web opens

Mutations printed a list row, or nothing, so a person could not tell
what changed and scripts parsed rows meant for people. Commands now get
the helpers for the gh convention:

- done and warn print "✓ Closed issue alice/x#5 (Fix login)" and
  "! … is already closed" to stderr, only when stdout is a terminal and
  --json is not set.
- printURL prints a created resource's URL to stdout unless --json is
  set, so url=$(tea issue create …) works.
- batchDone applies a mutation to several selections like batch and
  reports each success with a done line instead of a table.
- issueRef formats "alice/x#5 (title)" references.

--web now prints "Opening localhost:3001/alice/project/issues/1 in your
browser." to stderr on a terminal before the browser starts.

Signed-off-by: bircni <bircni@icloud.com>

internal/app/human_output.go

@@ -133,15 +133,48 @@ func writeView[T any](a *application, cmd *cobra.Command, item T, view func(T) t
 	return a.writeHuman(cmd, view(item).Render(a.display()))
 }
 
+// done reports a completed mutation on stderr, such as "✓ Closed issue alice/x#5 (Fix login)",
+// when people read stdout: on a TTY and without --json.
+func (a *application) done(cmd *cobra.Command, format string, args ...any) {
+	a.feedback(cmd, "✓", "green", format, args...)
+}
+
+// warn reports a mutation that had nothing to do, such as "! Issue alice/x#5 (Fix login) is already
+// closed", under the same conditions as done.
+func (a *application) warn(cmd *cobra.Command, format string, args ...any) {
+	a.feedback(cmd, "!", "yellow", format, args...)
+}
+
+func (a *application) feedback(cmd *cobra.Command, icon, color, format string, args ...any) {
+	if !a.deps.Streams.OutTTY || a.options.json != "" {
+		return
+	}
+	fmt.Fprintln(cmd.ErrOrStderr(), terminal.Colorize(color, icon, a.colorEnabled())+" "+terminal.SafeLine(fmt.Sprintf(format, args...)))
+}
+
+// printURL writes the URL of a created resource to stdout unless --json is set, so scripts can
+// capture it: url=$(tea issue create …).
+func (a *application) printURL(cmd *cobra.Command, url string) error {
+	if a.options.json != "" {
+		return nil
+	}
+	_, err := fmt.Fprintln(cmd.OutOrStdout(), terminal.SafeLine(url))
+	return err
+}
+
+// issueRef names an issue or pull request in feedback: "alice/x#5 (Fix login)".
+func issueRef(repo string, number int64, title string) string {
+	return fmt.Sprintf("%s#%d (%s)", repo, number, title)
+}
+
 // abortBatch stops a batch instead of recording an item failure.
 type abortBatch struct{ error }
 
 func (e abortBatch) Unwrap() error { return e.error }
 
-// batch applies run to each selection and continues past individual failures, which
-// it reports prefixed with the selection's label. Human output is one table of the
-// results; JSON is an object for one selection (none if it failed), otherwise an array.
-func batch[K, T any](a *application, cmd *cobra.Command, keys []K, label func(K) string, run func(K) (T, error), row func(T) []terminal.Cell) error {
+// applyBatch applies run to each selection and continues past individual failures, which it
+// returns prefixed with the selection's label. succeeded sees each result as it arrives.
+func applyBatch[K, T any](cmd *cobra.Command, keys []K, label func(K) string, run func(K) (T, error), succeeded func(T)) ([]T, []error) {
 	results := []T{}
 	var failures []error
 	for _, key := range keys {
@@ -159,15 +192,42 @@ func batch[K, T any](a *application, cmd *cobra.Command, keys []K, label func(K)
 			continue
 		}
 		results = append(results, item)
+		succeeded(item)
 	}
-	var err error
+	return results, failures
+}
+
+// writeBatchJSON writes an object for one selection (none if it failed), otherwise an array.
+func writeBatchJSON[T any](a *application, cmd *cobra.Command, selections int, results []T) error {
 	switch {
-	case a.options.json == "":
-		err = a.writeHuman(cmd, legacyTable(a, cmd, results, row))
-	case len(keys) != 1:
-		err = a.writeJSON(cmd, results)
+	case selections != 1:
+		return a.writeJSON(cmd, results)
 	case len(results) == 1:
-		err = a.writeJSON(cmd, results[0])
+		return a.writeJSON(cmd, results[0])
+	}
+	return nil
+}
+
+// batch applies run to each selection like batchDone, for commands that predate it: its human
+// output is one table of the results.
+func batch[K, T any](a *application, cmd *cobra.Command, keys []K, label func(K) string, run func(K) (T, error), row func(T) []terminal.Cell) error {
+	results, failures := applyBatch(cmd, keys, label, run, func(T) {})
+	var err error
+	if a.options.json == "" {
+		err = a.writeHuman(cmd, legacyTable(a, cmd, results, row))
+	} else {
+		err = writeBatchJSON(a, cmd, len(keys), results)
+	}
+	return errors.Join(append(failures, err)...)
+}
+
+// batchDone applies a mutation to each selection like batch, reporting each success with a done
+// line from report, such as "Closed issue alice/x#5 (Fix login)", and the results as JSON.
+func batchDone[K, T any](a *application, cmd *cobra.Command, keys []K, label func(K) string, run func(K) (T, error), report func(T) string) error {
+	results, failures := applyBatch(cmd, keys, label, run, func(item T) { a.done(cmd, "%s", report(item)) })
+	var err error
+	if a.options.json != "" {
+		err = writeBatchJSON(a, cmd, len(keys), results)
 	}
 	return errors.Join(append(failures, err)...)
 }
@@ -181,7 +241,8 @@ func writeList[T any](a *application, cmd *cobra.Command, items []T, row func(T)
 	return a.writeHuman(cmd, legacyTable(a, cmd, items, row))
 }
 
-// writeItem writes one item as a JSON object, or as its list row. Views move to writeView.
+// writeItem writes one item as a JSON object, or as its list row. Views move to writeView, and
+// mutations to done and printURL.
 func writeItem[T any](a *application, cmd *cobra.Command, item T, row func(T) []terminal.Cell) error {
 	if a.options.json != "" {
 		return a.writeJSON(cmd, item)