refactor: add terminal output and forms package (#1124)

- `internal/terminal`: streams and the prompting policy, interactive forms (issue, PR, review, merge, milestone), editor / pager / browser launching, JSON and `--jq` output.
- An aligned table renderer and a record renderer for human output; both strip control and escape characters from server-supplied text so titles and bodies cannot inject terminal sequences.

Reviewed-on: https://gitea.com/gitea/tea/pulls/1124
Reviewed-by: TheFox0x7 <95654+thefox0x7@noreply.gitea.com>

internal/terminal/issue_edit_form_test.go

@@ -0,0 +1,45 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package terminal
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestEditIssueEditBodyPreservesDraftOnFailure(t *testing.T) {
+	p, _ := testPrompter(bytes.NewBufferString("New Title\r"))
+	path := filepath.Join(t.TempDir(), "draft.md")
+	values, err := p.EditIssue(context.Background(), IssueEditFormChoices{
+		Title: "", Body: "current",
+		EditBody: func(context.Context, string) (Draft, error) {
+			return Draft{Path: path, Body: "partial"}, errors.New("editor failed")
+		},
+	})
+	require.ErrorContains(t, err, "editor failed")
+	require.Equal(t, path, values.Draft.Path)
+	require.Equal(t, "New Title", values.Title)
+}
+
+func TestEditIssueKeepsUnchangedDeadline(t *testing.T) {
+	deadline := time.Date(2026, 10, 6, 23, 59, 59, 0, time.FixedZone("server", -5*3600))
+	p, _ := testPrompter(bytes.NewBufferString("\r\r\r"))
+	values, err := p.EditIssue(context.Background(), IssueEditFormChoices{Title: "Title", Deadline: &deadline, CanPush: true})
+	require.NoError(t, err)
+	require.Nil(t, values.Deadline)
+	require.False(t, values.ClearDeadline)
+}
+
+func TestWithCurrentKeepsSeededValuesSelectable(t *testing.T) {
+	options := []IssueLabelChoice{{Name: "bug", ID: 2}}
+	merged := withCurrent(options, IssueLabelChoice{Name: "bug", ID: 2}, IssueLabelChoice{Name: "org", ID: 7})
+	require.Equal(t, []IssueLabelChoice{{Name: "bug", ID: 2}, {Name: "org", ID: 7}}, merged)
+	require.Len(t, options, 1)
+}