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/pager_test.go

@@ -0,0 +1,88 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package terminal
+
+import (
+	"bytes"
+	"context"
+	"io"
+	"os"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"testing"
+
+	"github.com/kballard/go-shellquote"
+	"github.com/stretchr/testify/require"
+)
+
+type recordingPager struct {
+	command string
+	input   string
+	calls   int
+}
+
+func (p *recordingPager) Page(_ context.Context, command string, input io.Reader, streams Streams) error {
+	p.calls++
+	p.command = command
+	data, err := io.ReadAll(input)
+	if err != nil {
+		return err
+	}
+	p.input = string(data)
+	_, err = streams.Out.Write(append([]byte("PAGED:"), data...))
+	return err
+}
+
+func TestWriteHumanPagesMultiLineTTYOutput(t *testing.T) {
+	out := &bytes.Buffer{}
+	pager := &recordingPager{}
+	streams := Streams{Out: out, OutTTY: true}
+	require.NoError(t, WriteHuman(context.Background(), streams, "less -R", pager, "one\ntwo\n"))
+	require.Equal(t, 1, pager.calls)
+	require.Equal(t, "less -R", pager.command)
+	require.Equal(t, "one\ntwo\n", pager.input)
+	require.Equal(t, "PAGED:one\ntwo\n", out.String())
+}
+
+func TestWriteHumanSkipsPagerWhenNotNeeded(t *testing.T) {
+	for _, tc := range []struct {
+		name    string
+		streams Streams
+		command string
+		text    string
+	}{
+		{"non-tty", Streams{OutTTY: false}, "less", "one\ntwo\n"},
+		{"empty pager", Streams{OutTTY: true}, "", "one\ntwo\n"},
+		{"cat disables", Streams{OutTTY: true}, "cat", "one\ntwo\n"},
+		{"single line", Streams{OutTTY: true}, "less", "one\n"},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			out := &bytes.Buffer{}
+			tc.streams.Out = out
+			pager := &recordingPager{}
+			require.NoError(t, WriteHuman(context.Background(), tc.streams, tc.command, pager, tc.text))
+			require.Zero(t, pager.calls)
+			require.Equal(t, tc.text, out.String())
+		})
+	}
+}
+
+func TestSystemPagerUsesLiteralArguments(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("pager fixture uses a POSIX executable")
+	}
+	directory := t.TempDir()
+	program := filepath.Join(directory, "pager with spaces")
+	capture := filepath.Join(directory, "captured")
+	require.NoError(t, os.WriteFile(program, []byte("#!/bin/sh\ncat > \"$1\"\n"), 0o700))
+	out, diagnostics := &bytes.Buffer{}, &bytes.Buffer{}
+	command := shellquote.Join(program, capture)
+	require.NoError(t, (SystemPager{}).Page(context.Background(), command, strings.NewReader("paged body\n"), Streams{Out: out, ErrOut: diagnostics}))
+	data, err := os.ReadFile(capture)
+	require.NoError(t, err)
+	require.Equal(t, "paged body\n", string(data))
+	require.Empty(t, out.String())
+	require.Empty(t, diagnostics.String())
+}